Linux kernel nfsd is widely deployed; a remotely-triggerable race can crash kernels on NFS servers, risking widespread disruption to server infrastructure.
CVE-2026-89686
Race in Linux nfsd can trigger kernel panic via NFS delegation.
Is CVE-2026-89686 being exploited?
Not confirmed. CVE-2026-89686 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 0.67% probability of exploitation in the next 30 days.
How severe is CVE-2026-89686?
CVE-2026-89686 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-2026-89686?
Yes. A fix has been recorded for CVE-2026-89686. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89686 affect?
CVE-2026-89686 affects Linux kernel nfsd (NFSv4 server), Linux servers exposing NFS delegations. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89686?
Apply kernel updates with the nfsd fix and restrict NFS access until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote NFS clients can trigger a kernel BUG_ON leading to kernel panic/denial-of-service; may enable further kernel compromise in worst cases.
Immediate action required
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < c517f27498757e616d2a8fe6d16caad1fee422e6
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 607a56fea772c1f4f4989d8e255dd4f7192d9604
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 97bda8b4284d90897a1f1922e5082ff9e35d7c7e
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < ca94ba36172046be6a694a7986f6931e47ed4d51
- affected4.0
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.