CVE-2026-63795
A critical flaw in the Linux kernel’s 9p filesystem can cause a use‑after‑free or reference‑count underflow when a failed walk operation incorrectly releases a file identifier that is still in use. The issue has been fixed in the kernel source. Users should update to a kernel version that includes the patch.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel, any distribution that uses the 9p filesystem implementation, especially those that perform multi‑component walk operations.
Real-world impact
An attacker could trigger a kernel crash or potentially gain elevated privileges by exploiting the use‑after‑free or reference‑count underflow.
Why this severity
The CVSS score of 10 reflects that the vulnerability is exploitable over the network with no authentication or user interaction, and it can compromise confidentiality, integrity, and availability.
What to do about it
- 01Upgrade the Linux kernel to a version that includes the 9p filesystem fix.
- 02Reboot the system to load the updated kernel.
NVD description indicates fix
Timeline
- Jul 19, 2026 · 14d agoPublishedDisclosed and added to the National Vulnerability Database.
- Jul 20, 2026 · 13d agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.
- Jul 30, 2026 · 3d agoAdvisory updatedThe NVD record was last revised.