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… (CVE-2026-63795)
A use-after-free or reference count underflow vulnerability was resolved in the Linux kernel's 9p client code. The issue occurs in the p9_client_walk() function when called with clone set to false, causing an oldfid alias to be improperly released on an error path. This can lead to oldfid being destroyed while still in use by the caller, potentially causing memory corruption.
AI Analysis
Technical Summary
The vulnerability in the Linux kernel's 9p client implementation involves improper reference counting in the p9_client_walk() function. When clone is false, fid aliases oldfid, but if a walk fails after the request is sent, the error path unconditionally calls p9_fid_put(fid), dropping a reference to oldfid incorrectly. If this was the last reference, oldfid is destroyed prematurely, leading to use-after-free or refcount underflow conditions. The fix ensures fid is only put in the error path when it does not alias oldfid, preventing premature destruction.
Potential Impact
This vulnerability can cause use-after-free or reference count underflow in the Linux kernel's 9p client code, potentially leading to memory corruption or kernel instability. There is no indication of known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
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… (CVE-2026-63795)
Description
A use-after-free or reference count underflow vulnerability was resolved in the Linux kernel's 9p client code. The issue occurs in the p9_client_walk() function when called with clone set to false, causing an oldfid alias to be improperly released on an error path. This can lead to oldfid being destroyed while still in use by the caller, potentially causing memory corruption.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in the Linux kernel's 9p client implementation involves improper reference counting in the p9_client_walk() function. When clone is false, fid aliases oldfid, but if a walk fails after the request is sent, the error path unconditionally calls p9_fid_put(fid), dropping a reference to oldfid incorrectly. If this was the last reference, oldfid is destroyed prematurely, leading to use-after-free or refcount underflow conditions. The fix ensures fid is only put in the error path when it does not alias oldfid, preventing premature destruction.
Potential Impact
This vulnerability can cause use-after-free or reference count underflow in the Linux kernel's 9p client code, potentially leading to memory corruption or kernel instability. There is no indication of known exploits in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-jj7f-gfpp-fxfg
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-63795"]
- Ecosystems
- []
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a5d27ad2a4a8d59891318e1
Added to database: 07/19/2026, 19:38:21 UTC
Last enriched: 07/19/2026, 20:20:34 UTC
Last updated: 07/20/2026, 17:26:47 UTC
Views: 10
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