Jenkins Pipeline Maven Integration Plugin 3.9.2 and earlier does not escape the upstream job's display name shown as part of a build cause, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

This advisory announces vulnerabilities in the following Jenkins deliverables:

*   android-lint Plugin
*   Blue Ocean Plugin
*   chosen-views-tabbar Plugin
*   ClearCase Release Plugin
*   computer-queue-plugin Plugin
*   Copy data to workspace Plugin
*   Coverage/Complexity Scatter Plot Plugin
*   Custom Job Icon Plugin
*   Description Column Plugin
*   ElasTest Plugin
*   Email Extension Plugin
*   Health Advisor by CloudBees Plugin
*   Locked Files Report Plugin
*   Mailer Plugin
*   MongoDB Plugin
*   Perfecto Plugin
*   Pipeline Maven Integration Plugin
*   Radiator View Plugin
*   Selection tasks Plugin
*   Storable Configs Plugin
*   Validating String Parameter Plugin

**Descriptions****Missing hostname validation in Mailer Plugin**

**SECURITY-1813 / CVE-2020-2252**  
**Severity (CVSS):** Medium  
**Affected plugin: mailer**  
**Description:**

Mailer Plugin 1.32 and earlier does not perform hostname validation when connecting to the configured SMTP server. This lack of validation could be abused using a man-in-the-middle attack to intercept these connections.

Mailer Plugin 1.32.1 validates the SMTP hostname when connecting via TLS by default. In Mailer Plugin 1.32 and earlier, administrators can set the Java system property mail.smtp.ssl.checkserveridentity to true on startup to enable this protection.

In case of problems, this protection can be disabled again by setting the Java system property mail.smtp.ssl.checkserveridentity to false on startup.

**Missing hostname validation in Email Extension Plugin**

**SECURITY-1851 / CVE-2020-2253**  
**Severity (CVSS):** Medium  
**Affected plugin: email-ext**  
**Description:**

Email Extension Plugin 2.75 and earlier does not perform hostname validation when connecting to the configured SMTP server. This lack of validation could be abused using a man-in-the-middle attack to intercept these connections.

Email Extension Plugin 2.76 validates the SMTP hostname when connecting via TLS by default. In Email Extension Plugin 2.75 and earlier, administrators can set the Java system property mail.smtp.ssl.checkserveridentity to true on startup to enable this protection. Alternatively, this protection can be enabled (or disabled in the new version) via the 'Advanced Email Properties' field in the plugin’s configuration in Configure System.

In case of problems, this protection can be disabled again by setting mail.smtp.ssl.checkserveridentity to false using either method.

**Path traversal vulnerability in Blue Ocean Plugin**

**SECURITY-1956 / CVE-2020-2254**  
**Severity (CVSS):** Medium  
**Affected plugin: blueocean**  
**Description:**

Blue Ocean Plugin 1.23.2 and earlier provides an undocumented feature flag, blueocean.features.GIT_READ_SAVE_TYPE, that when set to the value clone allows an attacker with Item/Configure or Item/Create permission to read arbitrary files on the Jenkins controller file system.

Blue Ocean Plugin 1.23.3 no longer includes this feature and redirects existing usage to a safer alternative.

**Missing permission check in Blue Ocean Plugin**

**SECURITY-1961 / CVE-2020-2255**  
**Severity (CVSS):** Medium  
**Affected plugin: blueocean**  
**Description:**

**Updated 2020-09-16:** _This entry previously misidentified the problematic behavior. The HTTP request itself is legitimate, but only authorized users should be able to perform it._

Blue Ocean Plugin 1.23.2 and earlier does not perform permission checks in several HTTP endpoints implementing connection tests.

This allows attackers with Overall/Read permission to connect to an attacker-specified URL.

Blue Ocean Plugin 1.23.3 requires Item/Create permission to perform these connection tests.

**Stored XSS vulnerability in upstream cause in Pipeline Maven Integration Plugin**

**SECURITY-1976 / CVE-2020-2256**  
**Severity (CVSS):** High  
**Affected plugin: pipeline-maven**  
**Description:**

Pipeline Maven Integration Plugin 3.9.2 and earlier does not escape the upstream job’s display name shown as part of a build cause.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

Pipeline Maven Integration Plugin 3.9.3 escapes upstream job names in build causes.

**Stored XSS vulnerability in Validating String Parameter Plugin**

**SECURITY-1935 / CVE-2020-2257**  
**Severity (CVSS):** High  
**Affected plugin: validating-string-parameter**  
**Description:**

Validating String Parameter Plugin 2.4 and earlier does not escape regular expressions in tooltips. Additionally, Validating String Parameter Plugin 2.4 does not escape parameter names and parameter descriptions.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

Validating String Parameter Plugin 2.5 escapes regular expressions in tooltips and parameter names. Parameter descriptions are rendered using the configured markup formatter.

**Incorrect permission check in Health Advisor by CloudBees Plugin**

**SECURITY-1998 / CVE-2020-2258**  
**Severity (CVSS):** Medium  
**Affected plugin: cloudbees-jenkins-advisor**  
**Description:**

Health Advisor by CloudBees Plugin 3.2.0 and earlier does not correctly perform a permission check in an HTTP endpoint.

This allows attackers with Overall/Read permission to view an administrative configuration page.

Health Advisor by CloudBees Plugin 3.2.1 requires Overall/Administer to view its administrative configuration page.

**Stored XSS vulnerability in computer-queue-plugin Plugin**

**SECURITY-1912 / CVE-2020-2259**  
**Severity (CVSS):** High  
**Affected plugin: computer-queue-plugin**  
**Description:**

computer-queue-plugin Plugin 1.5 and earlier does not escape the agent name in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Agent/Configure permission.

computer-queue-plugin Plugin 1.6 escapes the agent name in tooltips.

**Missing permission check in Perfecto Plugin**

**SECURITY-1979 / CVE-2020-2260**  
**Severity (CVSS):** Medium  
**Affected plugin: perfecto**  
**Description:**

Perfecto Plugin 1.17 and earlier does not perform a permission check in a method implementing a connection test.

This allows attackers with Overall/Read permission to connect to an attacker-specified HTTP URL using attacker-specified username and password.

Perfecto Plugin 1.18 requires Overall/Administer permission to perform a connection test.

**OS command execution vulnerability in Perfecto Plugin**

**SECURITY-1980 / CVE-2020-2261**  
**Severity (CVSS):** High  
**Affected plugin: perfecto**  
**Description:**

Perfecto Plugin allows specifying Perfecto Connect Path and Perfecto Connect File Name in job configurations.

This command is executed on the Jenkins controller in Perfecto Plugin 1.17 and earlier, allowing attackers with Job/Configure permission to run arbitrary commands on the Jenkins controller.

Perfecto Plugin 1.18 executes the specified commands on the agent the build is running on.

**Stored XSS vulnerability in android-lint Plugin**

**SECURITY-1908 / CVE-2020-2262**  
**Severity (CVSS):** High  
**Affected plugin: android-lint**  
**Description:**

android-lint Plugin 2.6 and earlier does not escape the annotation message in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to provide report files to the 'Publish Android Lint results' post-build step.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in Radiator View Plugin**

**SECURITY-1927 / CVE-2020-2263**  
**Severity (CVSS):** High  
**Affected plugin: radiatorviewplugin**  
**Description:**

Radiator View Plugin 1.29 and earlier does not escape the full name of the jobs in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in Custom Job Icon Plugin**

**SECURITY-1914 / CVE-2020-2264**  
**Severity (CVSS):** High  
**Affected plugin: custom-job-icon**  
**Description:**

Custom Job Icon Plugin 0.2 and earlier does not escape the job descriptions in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in Coverage/Complexity Scatter Plot Plugin**

**SECURITY-1913 / CVE-2020-2265**  
**Severity (CVSS):** High  
**Affected plugin: covcomplplot**  
**Description:**

Coverage/Complexity Scatter Plot Plugin 1.1.1 and earlier does not escape the method information in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to provide report files to the 'Publish Coverage / Complexity Scatter Plot' post-build step.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in Description Column Plugin**

**SECURITY-1916 / CVE-2020-2266**  
**Severity (CVSS):** High  
**Affected plugin: description-column-plugin**  
**Description:**

Description Column Plugin 1.3 and earlier does not escape the job description in the column tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

As of publication of this advisory, there is no fix.

**CSRF vulnerability and missing permission checks in MongoDB Plugin**

**SECURITY-1904 / CVE-2020-2267 (missing permission check), CVE-2020-2268 (CSRF)**  
**Severity (CVSS):** Medium  
**Affected plugin: mongodb**  
**Description:**

MongoDB Plugin 1.3 and earlier does not perform permission checks in methods implementing form validation.

This allows attackers with Overall/Read permission to gain access to some metadata of any arbitrary files on the Jenkins controller.

Additionally, these form validation methods do not require POST requests, resulting in a cross-site request forgery (CSRF) vulnerability.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in chosen-views-tabbar Plugin**

**SECURITY-1869 / CVE-2020-2269**  
**Severity (CVSS):** High  
**Affected plugin: chosen-views-tabbar**  
**Description:**

chosen-views-tabbar Plugin 1.2 and earlier does not escape view names in the dropdown to select views.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with the ability to configure views.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in ClearCase Release Plugin**

**SECURITY-1911 / CVE-2020-2270**  
**Severity (CVSS):** High  
**Affected plugin: clearcase-release**  
**Description:**

ClearCase Release Plugin 0.3 and earlier does not escape the composite baseline in badge tooltip.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

As of publication of this advisory, there is no fix.

**Stored XSS vulnerability in Locked Files Report Plugin**

**SECURITY-1921 / CVE-2020-2271**  
**Severity (CVSS):** High  
**Affected plugin: locked-files-report**  
**Description:**

Locked Files Report Plugin 1.6 and earlier does not escape locked files' names in tooltips.

This results in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

As of publication of this advisory, there is no fix.

**CSRF vulnerability and missing permission checks in ElasTest Plugin**

**SECURITY-1903 / CVE-2020-2272 (missing permission check), CVE-2020-2273 (CSRF)**  
**Severity (CVSS):** Medium  
**Affected plugin: elastest**  
**Description:**

ElasTest Plugin 1.2.1 and earlier does not perform a permission check in a method implementing form validation.

This allows attackers with Overall/Read permission to connect to an attacker-specified URL using attacker-specified credentials.

Additionally, this form validation method does not require POST requests, resulting in a cross-site request forgery (CSRF) vulnerability.

As of publication of this advisory, there is no fix.

**Passwords stored in plain text by ElasTest Plugin**

**SECURITY-2014 / CVE-2020-2274**  
**Severity (CVSS):** Low  
**Affected plugin: elastest**  
**Description:**

ElasTest Plugin 1.2.1 and earlier stores its server password in plain text in the global configuration file jenkins.plugins.elastest.ElasTestInstallation.xml. This password can be viewed by users with access to the Jenkins controller file system.

As of publication of this advisory, there is no fix.

**Arbitrary file read vulnerability in Copy data to workspace Plugin**

**SECURITY-1966 / CVE-2020-2275**  
**Severity (CVSS):** Medium  
**Affected plugin: copy-data-to-workspace-plugin**  
**Description:**

Copy data to workspace Plugin allows users to copy files from the Jenkins controller to job workspaces.

Copy data to workspace Plugin 1.0 and earlier does not limit which directories can be copied. This allows attackers with Job/Configure permission to read arbitrary files on the Jenkins controller.

As of publication of this advisory, there is no fix.

**System command execution vulnerability in Selection tasks Plugin**

**SECURITY-1967 / CVE-2020-2276**  
**Severity (CVSS):** High  
**Affected plugin: selection-tasks-plugin**  
**Description:**

Selection tasks Plugin implements a job parameter that dynamically generates possible values from the output of a program. The path to that program is specified as part of the parameter configuration.

Selection tasks Plugin 1.0 and earlier executes this user-specified program on the Jenkins controller. This allows attackers with Job/Configure permission to execute an arbitrary system command on the Jenkins controller as the OS user that the Jenkins process is running as.

As of publication of this advisory, there is no fix.

**Arbitrary file read vulnerability in Storable Configs Plugin**

**SECURITY-1968 (1) / CVE-2020-2277**  
**Severity (CVSS):** Medium  
**Affected plugin: storable-configs-plugin**  
**Description:**

Storable Configs Plugin 1.0 and earlier allows users with Job/Read permission to read arbitrary files on the Jenkins controller.

As of publication of this advisory, there is no fix.

**Arbitrary file write vulnerability in Storable Configs Plugin**

**SECURITY-1968 (2) / CVE-2020-2278**  
**Severity (CVSS):** Medium  
**Affected plugin: storable-configs-plugin**  
**Description:**

Storable Configs Plugin allows storing copies of a job’s config.xml file on the Jenkins controller with a user-specified file name.

Storable Configs Plugin 1.0 and earlier does not restrict the user-specified file name, except that a .xml suffix is added if it’s not already present. This allows attackers with Job/Configure permission to replace any other .xml file on the Jenkins controller with the job’s config.xml file’s content.

As of publication of this advisory, there is no fix.

**Severity**

*   SECURITY-1813: Medium
*   SECURITY-1851: Medium
*   SECURITY-1869: High
*   SECURITY-1903: Medium
*   SECURITY-1904: Medium
*   SECURITY-1908: High
*   SECURITY-1911: High
*   SECURITY-1912: High
*   SECURITY-1913: High
*   SECURITY-1914: High
*   SECURITY-1916: High
*   SECURITY-1921: High
*   SECURITY-1927: High
*   SECURITY-1935: High
*   SECURITY-1956: Medium
*   SECURITY-1961: Medium
*   SECURITY-1966: Medium
*   SECURITY-1967: High
*   SECURITY-1968 (1): Medium
*   SECURITY-1968 (2): Medium
*   SECURITY-1976: High
*   SECURITY-1979: Medium
*   SECURITY-1980: High
*   SECURITY-1998: Medium
*   SECURITY-2014: Low

**Affected Versions**

*   **android-lint Plugin** up to and including 2.6
*   **Blue Ocean Plugin** up to and including 1.23.2
*   **chosen-views-tabbar Plugin** up to and including 1.2
*   **ClearCase Release Plugin** up to and including 0.3
*   **computer-queue-plugin Plugin** up to and including 1.5
*   **Copy data to workspace Plugin** up to and including 1.0
*   **Coverage/Complexity Scatter Plot Plugin** up to and including 1.1.1
*   **Custom Job Icon Plugin** up to and including 0.2
*   **Description Column Plugin** up to and including 1.3
*   **ElasTest Plugin** up to and including 1.2.1
*   **Email Extension Plugin** up to and including 2.75
*   **Health Advisor by CloudBees Plugin** up to and including 3.2.0
*   **Locked Files Report Plugin** up to and including 1.6
*   **Mailer Plugin** up to and including 1.32
*   **MongoDB Plugin** up to and including 1.3
*   **Perfecto Plugin** up to and including 1.17
*   **Pipeline Maven Integration Plugin** up to and including 3.9.2
*   **Radiator View Plugin** up to and including 1.29
*   **Selection tasks Plugin** up to and including 1.0
*   **Storable Configs Plugin** up to and including 1.0
*   **Validating String Parameter Plugin** up to and including 2.4

**Fix**

*   **Blue Ocean Plugin** should be updated to version 1.23.3
*   **computer-queue-plugin Plugin** should be updated to version 1.6
*   **Email Extension Plugin** should be updated to version 2.76
*   **Health Advisor by CloudBees Plugin** should be updated to version 3.2.1
*   **Mailer Plugin** should be updated to version 1.32.1
*   **Perfecto Plugin** should be updated to version 1.18
*   **Pipeline Maven Integration Plugin** should be updated to version 3.9.3
*   **Validating String Parameter Plugin** should be updated to version 2.5

These versions include fixes to the vulnerabilities described above. All prior versions are considered to be affected by these vulnerabilities unless otherwise indicated.

As of publication of this advisory, no fixes are available for the following plugins:

*   android-lint Plugin
*   chosen-views-tabbar Plugin
*   ClearCase Release Plugin
*   Copy data to workspace Plugin
*   Coverage/Complexity Scatter Plot Plugin
*   Custom Job Icon Plugin
*   Description Column Plugin
*   ElasTest Plugin
*   Locked Files Report Plugin
*   MongoDB Plugin
*   Radiator View Plugin
*   Selection tasks Plugin
*   Storable Configs Plugin

Learn why we announce these issues.

**Credit**

The Jenkins project would like to thank the reporters for discovering and reporting these vulnerabilities:

*   **Daniel Beck, CloudBees, Inc.** for SECURITY-1966, SECURITY-1967, SECURITY-1968 (1), SECURITY-1968 (2), SECURITY-1976
*   **Jinchen Sheng, Ant Security FG Lab.** for SECURITY-1956, SECURITY-1961
*   **Matt Sicker, CloudBees, Inc.** for SECURITY-1998
*   **Peter Stöckli (via Github Security Lab)** for SECURITY-1813
*   **Wadeck Follonier, CloudBees, Inc.** for SECURITY-1869, SECURITY-1903, SECURITY-1904, SECURITY-1908, SECURITY-1911, SECURITY-1912, SECURITY-1913, SECURITY-1914, SECURITY-1916, SECURITY-1921, SECURITY-1927, SECURITY-2014
*   **Wadeck Follonier, CloudBees, Inc. and Daniel Beck, CloudBees, Inc.** for SECURITY-1935

CVE-2020-2256: Jenkins Security Advisory 2020-09-16

Jenkins Radiator View Plugin 1.29 and earlier does not escape the full name of the jobs in tooltips, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

CVE-2020-2263: Jenkins Security Advisory 2020-09-16

Jenkins Custom Job Icon Plugin 0.2 and earlier does not escape the job descriptions in tooltips, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

CVE-2020-2264: Jenkins Security Advisory 2020-09-16

Jenkins Validating String Parameter Plugin 2.4 and earlier does not escape various user-controlled fields, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

CVE-2020-2257: Jenkins Security Advisory 2020-09-16

Jenkins Android Lint Plugin 2.6 and earlier does not escape the annotation message in tooltips, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to provide report files to the plugin's post-build step.

CVE-2020-2262: Jenkins Security Advisory 2020-09-16

Jenkins Coverage/Complexity Scatter Plot Plugin 1.1.1 and earlier does not escape the method information in tooltips, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers able to provide report files to the plugin's post-build step.

CVE-2020-2265: Jenkins Security Advisory 2020-09-16

Jenkins computer-queue-plugin Plugin 1.5 and earlier does not escape the agent name in tooltips, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Agent/Configure permission.

CVE-2020-2259: Jenkins Security Advisory 2020-09-16

Jenkins Description Column Plugin 1.3 and earlier does not escape the job description in the column tooltip, resulting in a stored cross-site scripting (XSS) vulnerability exploitable by attackers with Job/Configure permission.

CVE-2020-2266: Jenkins Security Advisory 2020-09-16

A flaw was found in ImageMagick in versions before 7.0.11 and before 6.9.12, where a division by zero in WaveImage() of MagickCore/visual-effects.c may trigger undefined behavior via a crafted image file submitted to an application using ImageMagick. The highest threat from this vulnerability is to system availability.

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**Bug 1946722** (CVE-2021-20309) - CVE-2021-20309 ImagemMagick: Division by zero in WaveImage() of MagickCore/visual-effects.c

Summary: CVE-2021-20309 ImagemMagick: Division by zero in WaveImage() of MagickCore/vi...

Keywords:

Status:

CLOSED NOTABUG

Alias:

CVE-2021-20309

Product:

Security Response

Classification:

Other

Component:

vulnerability

Sub Component:

Version:

unspecified

Hardware:

All

OS:

Linux

Priority:

low

Severity:

low

Target Milestone:

\---

Assignee:

Red Hat Product Security

QA Contact:

Docs Contact:

URL:

Whiteboard:

Depends On:

1946723 1946724 1947266

Blocks:

1946747 1946749

TreeView+

depends on / blocked

Reported:

2021-04-06 18:22 UTC by Pedro Sampaio

Modified:

2021-11-02 23:27 UTC (History)

CC List:

4 users (show)

Fixed In Version:

ImageMagick 7.0.11, ImageMagick 6.9.12

Doc Type:

If docs needed, set a value

Doc Text:

A flaw was found in ImageMagick, where a division by zero in WaveImage() of MagickCore/visual-effects.c may trigger undefined behavior via a crafted image file submitted to an application using ImageMagick. The highest threat from this vulnerability is to system availability.

Clone Of:

Environment:

Last Closed:

2021-11-02 23:27:29 UTC

  

Attachments

(Terms of Use)

Add an attachment (proposed patch, testcase, etc.)

  

Description Pedro Sampaio 2021-04-06 18:22:58 UTC

A flaw was found in ImageMagick before version 7.0.11 and 6.9.12. A division by zero in WaveImage() of MagickCore/visual-effects.c may trigger undefined behavior via crafted image file.

Upstream issue:

https://github.com/ImageMagick/ImageMagick/issues/3296

Upstream patch:

https://github.com/ImageMagick/ImageMagick/commit/94174beff065cb5683d09d79e992c3ebbdead311
https://github.com/ImageMagick/ImageMagick6/commit/f1e68d22d1b35459421710587a0dcbab6900b51f

Comment 1 Pedro Sampaio 2021-04-06 18:23:59 UTC

Created ImageMagick tracking bugs for this issue:

Affects: epel-8 \[bug 1946723\]
Affects: fedora-all \[bug 1946724\]

Comment 2 Todd Cullum 2021-04-06 21:04:43 UTC

Statement:

This flaw is out of support scope for Red Hat Enterprise Linux 6 and 7. It does not affect Red Hat Enterprise Linux 8 because the ImageMagick package is not shipped. To learn more about Red Hat Enterprise Linux support scope, please see https://access.redhat.com/support/policy/updates/errata/ .

Note You need to log in before you can comment on or make changes to this bug.

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CVE-2021-20309: Division by zero in WaveImage() of MagickCore/visual-effects.c

One of Microsoft's Patch Tuesday fixes has flipped from "Likely to be Exploited" to “Exploitation Detected”.

As it turns out, there was another actively exploited vulnerability included in Microsoft’s patch Tuesday updates for February.

When Microsoft said in its update guide for CVE-2024-21410 that the vulnerability was likely to be exploited by attackers, they weren’t kidding. Soon after they changed the status to “Exploitation Detected”.

Today, I was alerted to the fact after spotting a warning by the German Federal Office for Information Security (BSI) about the same vulnerability, Something the BSI does not do lightly.

The Exchange vulnerability is listed in the Common Vulnerabilities and Exposures (CVE) database as CVE-2024-21410, an elevation of privilege vulnerability with a CVSS score of 9.8 out of 10.

Microsoft’s description of the vulnerability is a bit more revealing:

> “An attacker could target an NTLM client such as Outlook with an NTLM credentials-leaking type vulnerability. The leaked credentials can then be relayed against the Exchange server to gain privileges as the victim client and to perform operations on the Exchange server on the victim’s behalf.”

In a Windows network, NTLM (New Technology LAN Manager) is a suite of Microsoft security protocols intended to provide authentication, integrity, and confidentiality to users. An attacker being able to impersonate a legitimate user could prove to be catastrophic.

Microsoft Exchange Servers, and mail servers in general, are central communication nodes in every organization and as such they are attractive targets for cybercriminals. Being able to perform a pass-the-hash attack would provide an attacker with a paved way into the heart of the network.

As part of the update, Microsoft has enabled Extended Protection for Authentication (EPA) by default with the Exchange Server 2019 Cumulative Update 14 (CU14). Without the protection enabled, an attacker can target Exchange Server to relay leaked NTLM credentials from other targets (for example Outlook).

If you are running Exchange Server 2019 CU13 or earlier and you have previously run the script that enables NTLM credentials Relay Protections then you are protected from this vulnerability. However, Microsoft strongly suggests installing the latest cumulative update.

Last year, Microsoft introduced Extended Protection support as an optional feature for Exchange Server 2016 CU23.

If you are unsure whether your organization has configured Extended Protection, you can use the latest version of the Exchange Server Health Checker script. The script will provide you with an overview of the Extended Protection status of your server.

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