#microsoft

### Description Microsoft is releasing this security advisory to provide information about a vulnerability in .NET 6.0, .NET 7.0 and .NET 8.0. This advisory also provides guidance on what developers can do to update their applications to address this vulnerability. A security feature bypass vulnerability exists when Microsoft .NET Framework-based applications use X.509 chain building APIs but do not completely validate the X.509 certificate due to a logic flaw. An attacker could present an arbitrary untrusted certificate with malformed signatures, triggering a bug in the framework. The framework will correctly report that X.509 chain building failed, but it will return an incorrect reason code for the failure. Applications which utilize this reason code to make their own chain building trust decisions may inadvertently treat this scenario as a successful chain build. This could allow an adversary to subvert the app's typical authentication logic. ### Affected software #### NuGet & ...

# Microsoft Security Advisory CVE-2024-21386: .NET Denial of Service Vulnerability ## <a name="executive-summary"></a>Executive summary Microsoft is releasing this security advisory to provide information about a vulnerability in ASP.NET 6.0, ASP.NET 7.0 and, ASP.NET 8.0 . This advisory also provides guidance on what developers can do to update their applications to address this vulnerability. A vulnerability exists in ASP.NET applications using SignalR where a malicious client can result in a denial-of-service. ## Announcement Announcement for this issue can be found at https://github.com/dotnet/announcements/issues/295 ### <a name="mitigation-factors"></a>Mitigation factors Microsoft has not identified any mitigating factors for this vulnerability. ## <a name="affected-software"></a>Affected software * Any .NET 6.0 application running on .NET 6.0.26 or earlier. * Any .NET 7.0 application running on .NET 7.0.15 or earlier. * Any .NET 8.0 application running on .NET 8.0.1 or ...

Although considered of moderate risk, one of the vulnerabilities is being actively exploited in the wild — CVE-2024-21351, a security feature bypass vulnerability in Windows SmartScreen.

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-g74q-5xw3-j7q9. This link is maintained to preserve external references. ## Original Description .NET Denial of Service Vulnerability

**According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is information disclosure?** The attack itself is carried out locally. For example, when the score indicates that the **Attack Vector** is **Local** (AV:L) and **User Interaction** is **Required** (UI:R), this could describe an exploit in which an attacker, through social engineering, convinces a victim to download and run a malicious application. This could lead to a local attack on the user's device which could leak data.

**According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is required (UI:R). What is the target context of the remote code execution?** An authenticated victim who is connected to the network must be tricked or persuaded to connect to a malicious SQL database using their SQL client application. After the connection is made, the server can send specially crafted replies to the client that exploit the vulnerability and permit execution of arbitrary code within the context of the user's SQL client application.

**According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is required (UI:R). What is the target context of the remote code execution?** An authenticated victim who is connected to the network must be tricked or persuaded to connect to a malicious SQL database using their SQL client application. After the connection is made, the server can send specially crafted replies to the client that exploit the vulnerability and permit execution of arbitrary code within the context of the user's SQL client application.

**According to the CVSS metric, a successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability?** An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.

**According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is required (UI:R). What is the target context of the remote code execution?** An authenticated victim who is connected to the network must be tricked or persuaded to connect to a malicious SQL database using their SQL client application. After the connection is made, the server can send specially crafted replies to the client that exploit the vulnerability and permit execution of arbitrary code within the context of the user's SQL client application.

**According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is required (UI:R). What is the target context of the remote code execution?** An authenticated victim who is connected to the network must be tricked or persuaded to connect to a malicious SQL database using their SQL client application. After the connection is made, the server can send specially crafted replies to the client that exploit the vulnerability and permit execution of arbitrary code within the context of the user's SQL client application.