CVE-2026-637959p: avoid putting oldfid in p9_client_walk() error path
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error path When p9_client_walk() is called with clone set to false, fid aliases oldfid. If the walk subsequently fails after the request has been sent, the error path jumps to clunk_fid, which currently calls p9_fid_put(fid) unconditionally. This drops a reference to oldfid even though ownership of oldfid remains with the caller. If this is the last reference, oldfid can be clunked and destroyed while the caller still expects it to be valid. A later use or put of oldfid can then trigger a use-after-free or refcount underflow. Fix this by only putting fid in the clunk_fid error path when it does not alias oldfid, matching the existing guard in the error path below. This can be triggered when a multi-component walk is split into multiple p9_client_walk() calls and a later non-cloning walk fails. A reproducer and refcount warning logs are available on request.
- CVSS
- 10.0 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before 99c379ca1e221c3d75c7c804ebbf4e5ee37a3070; from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before b84f46179c806450b89821221ea5bd9a1698aba8; from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before a61bdcba4f64c2f90d01461913f429ab151f1ca6; from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before 6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea; from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before a7656d368265d085ac9bb85ab31b0cdb72ad8c38; from b48dbb998d70b7f48c2ec0a15c3cf47136808e4e before 1a3860d46e3eb47dbd60339783cdad7904486b9f | CNA record |
linux linux_kernel linux:linux_kernel | from 6.0 before 6.1.177; from 6.2 before 6.6.144; from 6.7 before 6.12.95; from 6.13 before 6.18.38; from 6.19 before 7.1.3 | NVD |
References
- https://git.kernel.org/stable/c/99c379ca1e221c3d75c7c804ebbf4e5ee37a3070patch
- https://git.kernel.org/stable/c/b84f46179c806450b89821221ea5bd9a1698aba8patch
- https://git.kernel.org/stable/c/a61bdcba4f64c2f90d01461913f429ab151f1ca6patch
- https://git.kernel.org/stable/c/6dbe9443d9f5f7fb6d319a7b77108853ae6c6beapatch
- https://git.kernel.org/stable/c/a7656d368265d085ac9bb85ab31b0cdb72ad8c38patch
- https://git.kernel.org/stable/c/1a3860d46e3eb47dbd60339783cdad7904486b9fpatch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.