Linux Kernel up to 6.13.2 mlx5 reconnects use after free

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.13.2. Affected by this vulnerability is the function reconnects of the component mlx5. Executing a manipulation can lead to use after free. This vulnerability is tracked as CVE-2025-21751. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.13.2. It has been declared as critical. This vulnerability affects the function reconnects of the component mlx5. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: HWS, change error flow on matcher disconnect Currently, when firmware failure occurs during matcher disconnect flow, the error flow of the function reconnects the matcher back and returns an error, which continues running the calling function and eventually frees the matcher that is being disconnected. This leads to a case where we have a freed matcher on the matchers list, which in turn leads to use-after-free and eventual crash. This patch fixes that by not trying to reconnect the matcher back when some FW command fails during disconnect. Note that we're dealing here with FW error. We can't overcome this problem. This might lead to bad steering state (e.g. wrong connection between matchers), and will also lead to resource leakage, as it is the case with any other error handling during resource destruction. However, the goal here is to allow the driver to continue and not crash the machine with use-after-free error.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2025-21751 since 12/29/2024. The exploitation appears to be easy. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 05/25/2026).

The vulnerability scanner Nessus provides a plugin with the ID 234946 (Amazon Linux 2023 : bpftool, kernel6.12, kernel6.12-modules-extra (ALAS2023-2025-948)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.13.3 or 6.14-rc1 eliminates this vulnerability. Applying the patch 23a86c76a1a197e8fbbbd0ce3e826eb58c471624/1ce840c7a659aa53a31ef49f0271b4fd0dc10296 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (234946) and CERT Bund (WID-SEC-2025-0453). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Siemens SIMATIC S7
• RESF Rocky Linux
• Dell NetWorker
• Dell Avamar
• Red Hat OpenShift
• IBM QRadar SIEM
• SolarWinds Security Event Manager
• Dell PowerProtect Data Domain
• Open Source Linux Kernel
• IBM DataPower Gateway
• Dell Secure Connect Gateway
• Dell PowerScale OneFS
• Dell ECS

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.13.0
• 6.13.1
• 6.13.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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