Linux Kernel afs afs_apply_status null pointer dereference

Summaryinfo

A vulnerability labeled as problematic has been found in Linux Kernel. Affected by this issue is the function afs_apply_status of the component afs. Such manipulation leads to null pointer dereference. This vulnerability is traded as CVE-2026-72377. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel (the affected version unknown) and classified as problematic. Affected by this issue is the function afs_apply_status of the component afs. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: afs: Remove setting of AS_RELEASE_ALWAYS for symlinks and mountpoints Regular AFS files correctly use afs_file_aops which have release_folio set as netfs_release_folio, so AS_RELEASE_ALWAYS is valid for them when fscache is enabled (set via afs_vnode_set_cache()). Symlinks and mountpoints in AFS use afs_dir_aops, which does not provide a release_folio callback. However, afs_apply_status() unconditionally calls mapping_set_release_always() for these. In such case when memory management code attempts to release folios, filemap_release_folio() checks folio_needs_release() which returns true due to AS_RELEASE_ALWAYS being set. Since there is no release_folio callback, it falls through to try_to_free_buffers(), which at present expects buffer_heads to be not null. For symlinks and mountpoints without buffer_heads, this causes pointer dereference. [dh: Added more bits that were missed]

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-72377 since 08/09/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. 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 08/15/2026).

Applying the patch 9d6b0f6d437e2f8350e08678e5e1d20c11c364f3 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

License

• open-source

Website

• Vendor: https://www.kernel.org/

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