Affects Linux kernel ksmbd, widely deployed; critical UAF risk could enable kernel compromise.
CVE-2026-31718
Linux kernel ksmbd UAF in close_fd after durable SMB session reconnect.
Is CVE-2026-31718 being exploited?
Not confirmed. CVE-2026-31718 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 0.36% probability of exploitation in the next 30 days.
How severe is CVE-2026-31718?
CVE-2026-31718 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-2026-31718?
Yes. A fix has been recorded for CVE-2026-31718. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-31718 affect?
CVE-2026-31718 affects Linux kernel with ksmbd SMB server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-31718?
Update kernel to patched release; reboot if required
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Kernel use-after-free may allow local privilege escalation to root via SMB session handling.
Patch when possible
- affected>= 8df4bcdb0a4232192b2445256c39b787d58ef14d and < 0000a7780e0e446a28a273572f6ea8f7f582f694
- affected>= c8efcc786146a951091588e5fa7e3c754850cb3c and < e33c65f011980b4ad4abfd93585ec2079856368f
- affected>= c8efcc786146a951091588e5fa7e3c754850cb3c and < 3d6682726c2d3a46d31dae88b8166786b09b03ad
- affected>= c8efcc786146a951091588e5fa7e3c754850cb3c and < b34fc42cfe922e551f7a27d3ac3bb016e41d7dd9
- affected>= c8efcc786146a951091588e5fa7e3c754850cb3c and < 235e32320a470fcd3998fb3774f2290a0eb302a1
- affected>= 6.6.32 and < 6.6.140
- affected6.9
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.