Remote code execution in the Linux kernel NFS server (nfsd) affects virtually all Linux distributions and can compromise servers running NFS—high-impact, widely deployed infrastructure.
CVE-2026-89660
Linux kernel nfsd use-after-free enabling remote code execution via NFSv4 state revocation.
Is CVE-2026-89660 being exploited?
Not confirmed. CVE-2026-89660 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 0.59% probability of exploitation in the next 30 days.
How severe is CVE-2026-89660?
CVE-2026-89660 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-2026-89660?
Yes. A fix has been recorded for CVE-2026-89660. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89660 affect?
CVE-2026-89660 affects Linux kernel (nfsd), NFSv4 servers, Linux distributions with NFS server enabled (RHEL, Ubuntu, Debian, SUSE). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89660?
Apply vendor kernel updates, restart NFS server (nfsd) or reboot, and restrict NFS access until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution on Linux NFS servers: a malicious or rogue NFSv4 client can trigger a use-after-free during state revocation and execute arbitrary code.
Immediate action required
- affected>= 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc and < 549bd9868e9d77b07ea94870940d64342829c6ad
- affected>= 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc and < bf1f948691523282cc4905bc6cd325e0c0b49e6a
- affected>= 1c13bf9f2e3cd5a59ef988c6c5a49fe0f02bcdfc and < e270e5a0778e5bff852c8862ce9576ce70359393
- affected6.9
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.