Affects the Linux kernel CIFS client, widely deployed across organizations; a remote SMB server can leak kernel memory, requiring org-wide mitigation.
CVE-2026-89631
Malicious SMB server can trigger kernel memory leak in Linux CIFS client
Is CVE-2026-89631 being exploited?
Not confirmed. CVE-2026-89631 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 0.45% probability of exploitation in the next 30 days.
How severe is CVE-2026-89631?
CVE-2026-89631 is rated Critical with a CVSS score of 9.1. 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-2026-89631?
Yes. A fix has been recorded for CVE-2026-89631. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89631 affect?
CVE-2026-89631 affects Linux kernel (CIFS/SMB client), Distributions with CIFS enabled, Systems mounting SMB shares. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89631?
Apply kernel updates with CIFS fix; avoid/unmount untrusted SMB servers; restrict SMB access
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote kernel memory disclosure to userspace via crafted SMB/CIFS Tree Connect; may expose sensitive kernel data and cause crashes.
Patch when possible
- affected>= cc20c031bb067eb3280a1c4b5c42295093e24863 and < 3be89e8039a85fa3b6cd5f9dcc4c1459eb356c2d
- affected>= cc20c031bb067eb3280a1c4b5c42295093e24863 and < 411e484fe71a7f1028de617447edad9cb6d9d68a
- affected>= cc20c031bb067eb3280a1c4b5c42295093e24863 and < 65deb18359341141d37dc86fc7853511be3c87a7
- affected2.6.30
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.