Headline
CVE-2021-1495: Cisco Security Advisory: Multiple Cisco Products Snort HTTP Detection Engine File Policy Bypass Vulnerabilities
Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP. The vulnerability is due to incorrect handling of specific HTTP header parameters. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a configured file policy for HTTP packets and deliver a malicious payload.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
Fixed Releases
At the time of publication, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerabilities described in this advisory and which release included the fix for these vulnerabilities.
Cisco FTD Software
Cisco FTD Software Release
First Fixed Release for these Vulnerabilities
Earlier than 6.2.21
Migrate to a fixed release.
6.2.2
Migrate to a fixed release.
6.2.3
Migrate to a fixed release.
6.3.0
Migrate to a fixed release.
6.4.0
6.4.0.12
6.5.0
Migrate to a fixed release.
6.6.0
6.6.42
6.7.0
6.7.0.2
1. Cisco FMC and FTD Software releases 6.0.1 and earlier, as well as releases 6.2.0 and 6.2.1, have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.
2. The First Fixed Release for the 6.6.0 code train was 6.6.3; however, due to upgrade issues associated with CSCvx86231 the recommended release is 6.6.4.
To upgrade to a fixed release of Cisco FTD Software, do one of the following:
- For devices that are managed by using Cisco Firepower Management Center (FMC), use the FMC interface to install the upgrade. After installation is complete, reapply the access control policy.
- For devices that are managed by using Cisco Firepower Device Manager (FDM), use the FDM interface to install the upgrade. After installation is complete, reapply the access control policy.
Cisco IOS XE Software and Cisco IOS XE SD-WAN Software
Cisco UTD Snort IPS Engine Software for IOS XE and Cisco UTD Engine for IOS XE SD-WAN Software1
First Fixed Release for these Vulnerabilities
Earlier than 16.12
Migrate to a fixed release.
16.12
16.12.5
17.1
Migrate to a fixed release.
17.2
Migrate to a fixed release.
17.3
17.3.3
17.4
17.4.1
1Starting with release 17.2.1, Cisco IOS XE Software and Cisco IOS XE SD-WAN Software share the same image file.
Open Source Snort
The open source Snort project releases 2.9.17.1 and later contain the fix for these vulnerabilities. For more information on open source Snort, see the Snort website.
Related news
Debian Linux Security Advisory 5354-1 - Multiple security vulnerabilities were discovered in snort, a flexible Network Intrusion Detection System, which could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition or bypass filtering technology on an affected device and ex-filtrate data from a compromised host.