{"cve":"CVE-2026-31611","nvd":{"published":"2026-04-24T15:16:40.360","modified":"2026-10-15T02:19:12.263","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: require 3 sub-authorities before reading sub_auth[2]\n\nparse_dacl() compares each ACE SID against sid_unix_NFS_mode and on\nmatch reads sid.sub_auth[2] as the file mode.  If sid_unix_NFS_mode is\nthe prefix S-1-5-88-3 with num_subauth = 2 then compare_sids() compares\nonly min(num_subauth, 2) sub-authorities so a client SID with\nnum_subauth = 2 and sub_auth = {88, 3} will match.\n\nIf num_subauth = 2 and the ACE is placed at the very end of the security\ndescriptor, sub_auth[2] will be  4 bytes past end_of_acl.  The\nout-of-band bytes will then be masked to the low 9 bits and applied as\nthe file's POSIX mode, probably not something that is good to have\nhappen.\n\nFix this up by forcing the SID to actually carry a third sub-authority\nbefore reading it at all.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","score":8.6},"cwes":[],"references":["https://git.kernel.org/stable/c/08f9e6d899b5c834bbcc239eae1bed58d9b15d2c","https://git.kernel.org/stable/c/46bbcd3ebfb3549c8da1838fc4493e79bd3241e7","https://git.kernel.org/stable/c/53370cf9090777774e07fd9a8ebce67c6cc333ab","https://git.kernel.org/stable/c/9401f86a224f37b50e6a3ccf1d46a70d5ef8af0a","https://git.kernel.org/stable/c/b5b5d5936a50497fb151c0b122899a6894721c2b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:09.003606135+00:00"},"epss":{"cve":"CVE-2026-31611","score":0.00375,"percentile":0.31176,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}