CVE-2026-89635: Linux kernel · ksmbd: only rebind the reopened file's own oplock on durable reconnect
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical.
Data as of 12 Nov 2026, 20:25 UTC
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
Weaponized: 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 12 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinux-aws-6.14pkg:deb/ubuntu/linux-aws-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-aws-6.17pkg:deb/ubuntu/linux-aws-6.17?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.14pkg:deb/ubuntu/linux-azure-6.14?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.17pkg:deb/ubuntu/linux-azure-6.17?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-fde-6.14pkg:deb/ubuntu/linux-azure-fde-6.14?arch=source&distro=nobleOther 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 is available that restricts oplock rebinding during durable reconnects to only the oplock owned by the file being reopened, preventing adoption of foreign oplocks. Users should apply the official kernel updates that address this issue. Since this is a kernel-level vulnerability, upgrading to patched kernel versions is the recommended mitigation. No alternative workarounds are indicated.
Description
CVE-2026-89635 is a critical vulnerability in the Linux kernel's ksmbd component related to durable reconnect handling of oplocks. The flaw allows a reconnecting session to incorrectly rebind oplocks owned by other sessions, leading to use-after-free memory corruption. This occurs when multiple sessions hold durable handles on the same file and disconnect, causing one session to adopt oplocks belonging to another. The issue can result in kernel memory corruption and potential system instability or compromise.
References
- ubuntu.com/security/CVE-2026-89635 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-89635 (opens in a new tab)
- git.kernel.org/linus/3f220a0a62e6b9b391c9d1f0e6580b05173cc7f7 (opens in a new tab)
- git.kernel.org/stable/c/3f220a0a62e6b9b391c9d1f0e6580b05173cc7f7 (opens in a new tab)
- git.kernel.org/stable/c/74e3ef4630f004c0de40c0540648a5a4033c6c9d (opens in a new tab)