Linux kernel flaw in SMB client affects widely deployed servers and endpoints; exploitable use-after-free can crash kernels or enable RCE, making it broadly newsworthy.
CVE-2026-89636
Use-after-free in Linux SMB client allows kernel RCE or crash via crafted SMB responses.
Is CVE-2026-89636 being exploited?
Not confirmed. CVE-2026-89636 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 0.65% probability of exploitation in the next 30 days.
How severe is CVE-2026-89636?
CVE-2026-89636 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-2026-89636?
Yes. A fix has been recorded for CVE-2026-89636. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-89636 affect?
CVE-2026-89636 affects Linux kernel (SMB/CIFS client). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-89636?
Apply vendor/kernel updates immediately and reboot affected hosts
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Malicious SMB server or response can trigger a use-after-free in kernel SMB client, causing kernel panic or potential remote kernel code execution.
Immediate action required
- affected>= 54be1f6c1c37498bba557049df646cc239fa37e3 and < 7507bd1885643d0461a6017767492450af1ce2a3
- affected>= 54be1f6c1c37498bba557049df646cc239fa37e3 and < 9ab46a13798a61d9d020b01d4e57efdabe6624fa
- affected>= 54be1f6c1c37498bba557049df646cc239fa37e3 and < 5baab40404a9393bcc0b7b8f1950bf2c307e0984
- affected>= 54be1f6c1c37498bba557049df646cc239fa37e3 and < b1b741cf8e7ce1b91d937e23decd3d3358748700
- affected5.0
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.