Linux Kernel xfrm lockdep state issue

Summaryinfo

A vulnerability categorized as critical has been discovered in Linux Kernel. Affected by this issue is the function lockdep of the component xfrm. Executing a manipulation can lead to state issue. This vulnerability appears as CVE-2025-40215. There is no available exploit. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability was found in Linux Kernel (affected version unknown). It has been declared as critical. This vulnerability affects the function lockdep of the component xfrm. The manipulation with an unknown input leads to a state issue vulnerability. The CWE definition for the vulnerability is CWE-371. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: xfrm: delete x->tunnel as we delete x The ipcomp fallback tunnels currently get deleted (from the various lists and hashtables) as the last user state that needed that fallback is destroyed (not deleted). If a reference to that user state still exists, the fallback state will remain on the hashtables/lists, triggering the WARN in xfrm_state_fini. Because of those remaining references, the fix in commit f75a2804da39 ("xfrm: destroy xfrm_state synchronously on net exit path") is not complete. We recently fixed one such situation in TCP due to defered freeing of skbs (commit 9b6412e6979f ("tcp: drop secpath at the same time as we currently drop dst")). This can also happen due to IP reassembly: skbs with a secpath remain on the reassembly queue until netns destruction. If we can't guarantee that the queues are flushed by the time xfrm_state_fini runs, there may still be references to a (user) xfrm_state, preventing the timely deletion of the corresponding fallback state. Instead of chasing each instance of skbs holding a secpath one by one, this patch fixes the issue directly within xfrm, by deleting the fallback state as soon as the last user state depending on it has been deleted. Destruction will still happen when the final reference is dropped. A separate lockdep class for the fallback state is required since we're going to lock x->tunnel while x is locked.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2025-40215 since 04/16/2025. 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 02/23/2026).

The vulnerability scanner Nessus provides a plugin with the ID 277482 (Linux Distros Unpatched Vulnerability : CVE-2025-40215), which helps to determine the existence of the flaw in a target environment.

Applying the patch b441cf3f8c4b8576639d20c8eb4aa32917602ecd is able to eliminate this problem. The bugfix is ready for download at git.kernel.org.

The vulnerability is also documented in the databases at Tenable (277482), EUVD (EUVD-2025-201157) and CERT Bund (WID-SEC-2025-2747). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Debian Linux
• Google Cloud Platform
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• Open Source Linux Kernel
• RESF Rocky Linux
• Microsoft Azure Linux

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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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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