CVE-2026-89536
CVE-2026-89536 is a critical race condition in the Linux kernel's SUNRPC module where improper reference management can cause premature cleanup of the lower transport during TLS handshake cancellation, potentially leading to resource leaks.
An official fix is available, so this entry is kept for 30 days and then removed automatically.
Who is affected
Linux kernel (no specific product listed)
Real-world impact
The vulnerability could allow denial-of-service conditions or memory corruption due to incorrect reference handling during handshake cancellation, though no public exploit has been reported.
Why this severity
Critical severity (CVSS 9.8) due to high impact on system stability and potential for resource exhaustion through improper cleanup of kernel objects.
What to do about it
- 01Update the Linux kernel to a version that includes the fix for CVE-2026-89536. The vulnerability has been resolved in the Linux kernel.
- 02Ensure the xs_tls_handshake_sync() function properly retains references to the lower transport even when cancellation occurs after the handshake completes.
- 03Verify that xs_tls_handshake_done() only releases the reference after signaling handshake_done, matching the server-side handshake lifetime handling pattern.
- ›Apply the latest stable Linux kernel version immediately if the system is exposed to potential exploitation.
- ›Monitor for any newly disclosed exploits via CISA KEV or other threat intelligence feeds.
- ›Consider implementing additional defensive measures such as increased timeout values or enhanced error handling around TLS handshakes in custom applications.
CISA KEV: no | Exploit-DB: no | NVD-referenced vendor advisory: Fix implemented in Linux kernel for CVE-2026-89536
Timeline
- Sep 11, 2026 · 2d agoPublishedDisclosed and added to the National Vulnerability Database.
- Sep 13, 2026 · 7h agoOfficial fix availableA vendor patch or mitigation now exists — see the remediation steps above.