{"id":"CVE-2026-31611","revision":"c7dbd04a7e284e358d27ff22d10e703e","records":[{"revision":"c7dbd04a7e284e358d27ff22d10e703e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-31611","aliases":[],"title":"ksmbd: require 3 sub-authorities before reading sub_auth[2]","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.","state":0,"publishedAt":"2026-04-24T14:42:32.124+00:00","modifiedAt":"2026-10-15T01:17:10.339+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/smb/server/smbacl.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"cf2148b880fb7c0fcd727202dbc4fd5d6998b9c2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"b5b5d5936a50497fb151c0b122899a6894721c2b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"08f9e6d899b5c834bbcc239eae1bed58d9b15d2c\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"d2454f4a002d08560a60f214f392e6491cf11560\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"46bbcd3ebfb3549c8da1838fc4493e79bd3241e7\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"9401f86a224f37b50e6a3ccf1d46a70d5ef8af0a\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9\",\n                            \"lessThan\": \"53370cf9090777774e07fd9a8ebce67c6cc333ab\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/smb/server/smbacl.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"5.15\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"5.15\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.175\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.136\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.83\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.24\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.19.14\",\n                            \"lessThanOrEqual\": \"6.19.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.1\",\n                            \"lessThanOrEqual\": \"7.0.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 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,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/cf2148b880fb7c0fcd727202dbc4fd5d6998b9c2","https://git.kernel.org/stable/c/b5b5d5936a50497fb151c0b122899a6894721c2b","https://git.kernel.org/stable/c/08f9e6d899b5c834bbcc239eae1bed58d9b15d2c","https://git.kernel.org/stable/c/d2454f4a002d08560a60f214f392e6491cf11560","https://git.kernel.org/stable/c/46bbcd3ebfb3549c8da1838fc4493e79bd3241e7","https://git.kernel.org/stable/c/9401f86a224f37b50e6a3ccf1d46a70d5ef8af0a","https://git.kernel.org/stable/c/53370cf9090777774e07fd9a8ebce67c6cc333ab"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31611","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-31611","identifiers":["CVE-2026-31611"]},"retained":false,"historicalAffected":[]}],"coverage":[]}