Kernel-level vulnerability in widely deployed Linux NFS server allowing heap corruption/RCE/DoS; impacts server infrastructure and is high-profile.
CVE-2026-89689
Linux nfsd use-after-free in nfsd4_sequence causing kernel heap corruption.
Is CVE-2026-89689 being exploited?
Not confirmed. CVE-2026-89689 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 0.60% probability of exploitation in the next 30 days.
How severe is CVE-2026-89689?
CVE-2026-89689 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-2026-89689?
Yes. A fix has been recorded for CVE-2026-89689. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89689 affect?
CVE-2026-89689 affects Linux kernel (nfsd NFSv4 server). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89689?
Apply vendor kernel updates immediately; restrict/limit NFS client access and firewall NFS ports.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote NFS client can trigger heap corruption by freeing in-use session slots, enabling kernel panic, privilege escalation or potential RCE.
Immediate action required
- affected>= fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 and < 72d40b103bb03f0124d3a3c8f71a30cbafaf6afa
- affected>= fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 and < b449b134e7762ddf98653a4b1d3e76d2d212ea64
- affected>= fc8738c68d0bbf5033dd98b4f63d277ecbd49fd7 and < f5d22e372f4ac3eb287037a488c29691d52a6330
- affected6.14
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.