CVE-2026-89536: Linux kernel · SUNRPC: wait for in-flight client TLS handshake callback
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix has been implemented to address this vulnerability by properly synchronizing the reference handling during TLS handshake cancellation and completion. Users should apply the official patches or updates that include this fix for the affected Linux kernel versions. Since this is not a cloud service, remediation requires updating the affected kernel versions.
Description
A vulnerability in the Linux kernel's SUNRPC subsystem involving the client TLS handshake callback xs_tls_handshake_sync() has been resolved. The issue relates to improper reference handling of the lower transport during handshake cancellation and completion, which could lead to premature freeing of resources. This flaw affects specific Linux kernel versions and has a high CVSS score of 9.8, indicating critical impact on confidentiality, integrity, and availability.
References
- nvd.nist.gov/vuln/detail/CVE-2026-89536 (opens in a new tab)
- git.kernel.org/stable/c/15431820f448e09f8029b670d5c82aa5917d4625 (opens in a new tab)
- git.kernel.org/stable/c/1de391e8b94e31b45c19c16dbf315e294810c7de (opens in a new tab)
- git.kernel.org/stable/c/7fbb6d2ab0391eb8d1f1a68e6bc263ef02cea61b (opens in a new tab)
- git.kernel.org/stable/c/a89dd597458848b463d284b15e42a8078beeb046 (opens in a new tab)
- ubuntu.com/security/CVE-2026-89536 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89536 (opens in a new tab)
- git.kernel.org/linus/a89dd597458848b463d284b15e42a8078beeb046 (opens in a new tab)