NFSv4: remove callback IDR entry on client allocation failure
Affects Linux kernels from 2.6.38 onward that set up NFSv4.0 clients. Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52 and 7.2.6.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Fix
- Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, and 2 more
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Linux kernel's NFSv4 client code is affected. A failed client allocation could leave a stale callback identifier pointing at freed memory, which a later NFSv4.0 callback lookup could use, potentially causing memory corruption or a crash.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
In the Linux kernel, the following vulnerability has been resolved: NFSv4: remove callback IDR entry on client allocation failure nfs4_alloc_client() allocates an NFSv4.0 callback identifier before it finishes setting up the client. If any later initialization step fails, the error path frees the nfs_client directly with nfs_free_client(). That bypasses nfs_put_client(), which is where the callback IDR entry is removed during normal teardown. A failed allocation can therefore leave cb_ident_idr pointing at a freed nfs_client. A later NFSv4.0 callback lookup by cb_ident would find the stale pointer and take a reference to it. Make the callback IDR removal helper callable by the allocation failure path, and remove the callback identifier before freeing the client. This was found by a local static-analysis checker for publish-before-free lifetime bugs and confirmed by manual inspection.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 68c721391b761dbe38d5b0094d2bb6e8489ad92b; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 9bfdd0f591307b5198826a0e7a5b2f35f87acd2d; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 7c4812eb96bdcafb31a65b12f2aa96659429d1d4; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in fc95ca82d5ae598c428ab5a00ae69f8526d59371; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 80b1c3d5a881f7d9081aa9f46da9742878a0f893; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 3f2387e8bfbc4efda5d77c3a11a028d0a119c48f; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in 5891c03e150920618db0e9c4ea2d772abacdcfd1; From f4eecd5da3422e82e88e36c33cbd2595eebcacb1 · fixed in d05c2007b3d84ccba11dc6e9cb3202768cc72f14
- Linux Linux
2.6.38
- KernelLinux
From 2.6.38 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6
References 8
git.kernel.org
- stable/c/68c721391b761dbe38d5b0094d2bb6e8489ad92b
- stable/c/9bfdd0f591307b5198826a0e7a5b2f35f87acd2d
- stable/c/7c4812eb96bdcafb31a65b12f2aa96659429d1d4
- stable/c/fc95ca82d5ae598c428ab5a00ae69f8526d59371
- stable/c/80b1c3d5a881f7d9081aa9f46da9742878a0f893
- stable/c/3f2387e8bfbc4efda5d77c3a11a028d0a119c48f
- stable/c/5891c03e150920618db0e9c4ea2d772abacdcfd1
- stable/c/d05c2007b3d84ccba11dc6e9cb3202768cc72f14
Questions about CVE-2026-90151
What does this mean?
When a later step in NFSv4.0 client setup fails, the callback identifier allocated earlier is not removed. A later callback lookup can then find a stale pointer to the freed client, take a reference to it, and trigger a use-after-free.Source: git.kernel.org
Am I affected, and how do I check?
Affected are Linux kernels from 2.6.38 up to the fixed releases for each stable branch, and the code path is NFSv4.0 client allocation. Check the running kernel version with uname -r and compare it against the fixed versions listed for each branch.Source: git.kernel.org
What should I do about it?
Upgrade to the fixed kernel for the stable branch in use: 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, or 7.2.6.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data