Linux Kernel up to 6.18.32/7.0.9 NFSD kmem_cache_destroy fi_fds information disclosure

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 6.18.32/7.0.9. Affected by this issue is the function kmem_cache_destroy of the component NFSD. Such manipulation of the argument fi_fds leads to information disclosure. This vulnerability is listed as CVE-2026-53026. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.32/7.0.9. It has been rated as problematic. Affected by this issue is the function kmem_cache_destroy of the component NFSD. The manipulation of the argument fi_fds with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg In nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already set by another thread, __nfs4_file_get_access should not be called to increment the nfs4_file access count since that was already done by the thread that added READ access to the file. The extra fi_access count in nfs4_file can prevent the corresponding nfsd_file from being freed. When stopping nfs-server service, these extra access counts trigger a BUG in kmem_cache_destroy() that shows nfsd_file object remaining on __kmem_cache_shutdown. This problem can be reproduced by running the Git project's test suite over NFS.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-53026 since 06/09/2026. 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 06/24/2026). This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 6.18.33 or 7.0.10 eliminates this vulnerability. Applying the patch 4584229395d0d65bd517780afe97ffea07cb2c3d/b81572b073441dfd32213e41857676d0dbff4665/b48f44f36e6607b2f818560f19deb86b4a9c717b 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.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.0.7
• 7.0.8
• 7.0.9

License

• open-source

Website

• Vendor: https://www.kernel.org/

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