Linux kernel vulnerability in Ceph client leads to kernel UAF; affects core OS storage stack widely used in enterprise and cloud—high-impact system-level risk.
CVE-2026-89655
Ceph client kernel use-after-free allowing kernel corruption and escalation.
Is CVE-2026-89655 being exploited?
Not confirmed. CVE-2026-89655 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.70% probability of exploitation in the next 30 days.
How severe is CVE-2026-89655?
CVE-2026-89655 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-89655?
Yes. A fix has been recorded for CVE-2026-89655. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89655 affect?
CVE-2026-89655 affects Linux kernel (Ceph client module), Ceph client nodes, Systems using in-kernel Ceph. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89655?
Install vendor/kernel updates or backports immediately
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Use-after-free in Ceph client can cause kernel crash, local privilege escalation or arbitrary kernel code execution when processing FLUSH_ACK.
Immediate action required
- affected>= e4500b5e35c213e0f97be7cb69328c0877203a79 and < 2701431aa3cc8b23efe6890182e7b04f5e76fab5
- affected>= e4500b5e35c213e0f97be7cb69328c0877203a79 and < fe46746087b5b9c5bb2d022df6c7819218494ced
- affected>= e4500b5e35c213e0f97be7cb69328c0877203a79 and < 2dba24dcd5050be4b7b119e6f0b01f62203b5d26
- affected>= e4500b5e35c213e0f97be7cb69328c0877203a79 and < 7af4c4f01305b0935adf6d4301b1ec407025485d
- affected4.8
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.