Answer in brief
CVE-2026-63795 records a Critical severity (CVSS 10.0) vulnerability in 9p: avoid putting oldfid in p9_client_walk() error path. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 10.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <99c379ca1e221c3d75c7c804ebbf4e5ee37a3070 || >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <b84f46179c806450b89821221ea5bd9a1698aba8 || >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a61bdcba4f64c2f90d01461913f429ab151f1ca6 || >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea || >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <a7656d368265d085ac9bb85ab31b0cdb72ad8c38 || >=b48dbb998d70b7f48c2ec0a15c3cf47136808e4e <1a3860d46e3eb47dbd60339783cdad7904486b9f | 99c379ca1e221c3d75c7c804ebbf4e5ee37a3070, b84f46179c806450b89821221ea5bd9a1698aba8, a61bdcba4f64c2f90d01461913f429ab151f1ca6, 6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea, a7656d368265d085ac9bb85ab31b0cdb72ad8c38, 1a3860d46e3eb47dbd60339783cdad7904486b9f |
| Linux/Linuxgeneric | 6.0 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.