Affects Linux kernel SMB CIFS client; widely deployed; could enable privilege escalation.
CVE-2026-31709
Linux kernel SMB client may allow privilege escalation via crafted DACL.
Is CVE-2026-31709 being exploited?
Not confirmed. CVE-2026-31709 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 0.26% probability of exploitation in the next 30 days.
How severe is CVE-2026-31709?
CVE-2026-31709 is rated High with a CVSS score of 8.8. 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-2026-31709?
Yes. A fix has been recorded for CVE-2026-31709. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-31709 affect?
CVE-2026-31709 affects Linux kernel (CIFS/SMB client). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-31709?
Update kernel to patched version; limit SMB exposure.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Privilege escalation on host via crafted DACL in SMB CIFS client.
Patch when possible
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < b8603d9ae6c9087662b098619996bc4a8064319d
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < c2abdebf72000a64603ced84d36ccbd164f11391
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < 8e47d297e7cf9a6029a0d38e7b22faba7d7aaf12
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < d92f3f0b22414e7515696a02224d0af55e3004a3
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < ff0ca46b13b9ef6edbcd238a3b6caacfef8ba0e5
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < b78db9bddc84136f6a0bb49e8883cf200dfb87a8
- affected>= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 and < 0a8cf165566ba55a39fd0f4de172119dd646d39a
- affected5.12
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.