CVE-2026-31611
8.6 · HIGHOverview
CVE-2026-31611 is a high-severity vulnerability affecting linux linux_kernel. It was published on April 24, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: require 3 sub-authorities before reading sub_auth[2]
parse_dacl() compares each ACE SID against sid_unix_NFS_mode and on
match reads sid.sub_auth[2] as the file mode. If sid_unix_NFS_mode is
the prefix S-1-5-88-3 with num_subauth = 2 then compare_sids() compares
only min(num_subauth, 2) sub-authorities so a client SID with
num_subauth = 2 and sub_auth = {88, 3} will match.
If num_subauth = 2 and the ACE is placed at the very end of the security
descriptor, sub_auth[2] will be 4 bytes past end_of_acl. The
out-of-band bytes will then be masked to the low 9 bits and applied as
the file's POSIX mode, probably not something that is good to have
happen.
Fix this up by forcing the SID to actually carry a third sub-authority
before reading it at all.
Remediation
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| linux | linux_kernel | >= 5.15, < 6.6.136 | Affected |
References
Frequently Asked Questions
What is CVE-2026-31611?
CVE-2026-31611 is a high-severity vulnerability affecting linux linux_kernel. It was published on April 24, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).
How severe is CVE-2026-31611?
This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-31611?
Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-31611?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-31611 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
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