CVE-2026-89654
A critical use‑after‑free bug was found in the Linux kernel’s Ceph MDS session handling. The flaw allows a session to be freed while another thread still accesses it, potentially crashing the system or enabling arbitrary code execution. The issue has been fixed in the kernel source.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel users running Ceph MDS services – any system that uses the Ceph distributed file system with the affected kernel version.
Real-world impact
An attacker could trigger the bug to crash the kernel, causing a denial of service, or exploit the freed memory to run arbitrary code with kernel privileges.
Why this severity
The CVSS score of 9.8 reflects that the vulnerability requires no authentication or user interaction, and it can compromise confidentiality, integrity, and availability of the entire system.
What to do about it
- 01Update your Linux kernel to a version that includes the fix for CVE-2026-89654.
- 02Reboot the system to load the updated kernel.
NVD-referenced vendor advisory
Timeline
- Sep 11, 2026 · 2d agoPublishedDisclosed and added to the National Vulnerability Database.
- Sep 13, 2026 · 7h agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.