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Review reviewCritical

CVE-2026-63795

Linux Linux, linux kernel

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...

CVSS
10
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.07.19
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 10

Vulnerability overview

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...

Affected product and versions

Product
Linux Linux, linux kernel
Affected versions
>= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < 99c379ca1e221c3d75c7c804ebbf4e5ee37a3070, >= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < b84f46179c806450b89821221ea5bd9a1698aba8, >= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < a61bdcba4f64c2f90d01461913f429ab151f1ca6, >= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < 6dbe9443d9f5f7fb6d319a7b77108853ae6c6bea, >= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < a7656d368265d085ac9bb85ab31b0cdb72ad8c38, >= b48dbb998d70b7f48c2ec0a15c3cf47136808e4e < 1a3860d46e3eb47dbd60339783cdad7904486b9f, >= 6.0, >= 6.0 < 6.1.177, >= 6.2 < 6.6.144, >= 6.7 < 6.12.95, >= 6.13 < 6.18.38, >= 6.19 < 7.1.3
Fixed versions
6.1.177, 6.6.144, 6.12.95, 6.18.38, 7.1.3

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Linux Linux, linux kernel and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE
CWE-416