Linux kernel nfsd is widely deployed; flaw can corrupt kernel memory, crash systems or enable privilege escalation/RCE, posing enterprise-wide risk.
CVE-2026-53399
Linux kernel NFS server use-after-free in layout stateid allowing kernel memory corruption.
Is CVE-2026-53399 being exploited?
Not confirmed. CVE-2026-53399 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 0.54% probability of exploitation in the next 30 days.
How severe is CVE-2026-53399?
CVE-2026-53399 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-2026-53399?
Yes. A fix has been recorded for CVE-2026-53399. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53399 affect?
CVE-2026-53399 affects Linux kernel (nfsd NFSv4 layout stateid). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53399?
Apply vendor kernel updates for nfsd, restart NFS services, and restrict NFS client access ASAP
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
NFSv4 layout stateid use-after-free leads to kernel memory corruption; may cause crashes, privilege escalation or remote code execution via malicious NFS client requests.
Immediate action required
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < d788ef40a7517d22c97ab01700e4ae4c611b6f2f
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 2e0a5d6d62600b8c614d1b55e50ef94035d6adf9
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 7bbb7ce74051c8be4b69ff44ce3db370600dae61
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 48a586e382e4db1dbf958d44b63e081df5f8ed04
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < d369e5edfaaf83a448016e2f1da392b2174be801
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 83c2b7797742339bb768f83935f7ca33950db138
- affected>= c5c707f96fc9a6e5a57ca5baac892673270abe3d and < 30d55c8aabb261bc3f427d6b9aae7ef6206063f9
- 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.