{"id":"CVE-2026-64138","state":"PUBLISHED","title":"ksmbd: validate SID in parent security descriptor during ACL inheritance","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate SID in parent security descriptor during ACL inheritance\n\nIntroduce smb_validate_ntsd_sid() helper to safely validate Owner SID\nand Group SID inside the NT Security Descriptor (smb_ntsd) retrieved\nfrom the parent directory.","publishedAt":"2026-07-19T15:40:31.760Z","updatedAt":"2026-10-30T12:27:36.259Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"f7c4dee323d9176b8d3f5c69018ee57ae0d4653c","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"8efbea0253b7fa2d1960cab0fed36544ca0b41ab","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"f0e5c9c663badc9982e6941322eef1cb17de0f11","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"18d8db24b0a5b7be4829238dd4022236df02d421","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"1c9d0646a9959752f11ca1080dc1ff26bd1756cb","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"69f030cf95488ae1186c72ac8c66fd279664ea7f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smbacl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smbacl.c"]}],"references":["https://git.kernel.org/stable/c/f7c4dee323d9176b8d3f5c69018ee57ae0d4653c","https://git.kernel.org/stable/c/8efbea0253b7fa2d1960cab0fed36544ca0b41ab","https://git.kernel.org/stable/c/f0e5c9c663badc9982e6941322eef1cb17de0f11","https://git.kernel.org/stable/c/18d8db24b0a5b7be4829238dd4022236df02d421","https://git.kernel.org/stable/c/1c9d0646a9959752f11ca1080dc1ff26bd1756cb","https://git.kernel.org/stable/c/69f030cf95488ae1186c72ac8c66fd279664ea7f"],"weaknesses":[],"ingestedAt":"2026-10-30T12:46:06.359Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64138.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64138","state":"PUBLISHED","datePublished":"2026-07-19T15:40:31.760Z","dateUpdated":"2026-10-30T12:27:36.259Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.037Z"},"containers":{"cna":{"title":"ksmbd: validate SID in parent security descriptor during ACL inheritance","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate SID in parent security descriptor during ACL inheritance\n\nIntroduce smb_validate_ntsd_sid() helper to safely validate Owner SID\nand Group SID inside the NT Security Descriptor (smb_ntsd) retrieved\nfrom the parent directory."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"f7c4dee323d9176b8d3f5c69018ee57ae0d4653c","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"8efbea0253b7fa2d1960cab0fed36544ca0b41ab","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"f0e5c9c663badc9982e6941322eef1cb17de0f11","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"18d8db24b0a5b7be4829238dd4022236df02d421","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"1c9d0646a9959752f11ca1080dc1ff26bd1756cb","versionType":"git"},{"version":"e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9","status":"affected","lessThan":"69f030cf95488ae1186c72ac8c66fd279664ea7f","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smbacl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.15","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.15","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.92","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.34","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.11","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smbacl.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/f7c4dee323d9176b8d3f5c69018ee57ae0d4653c"},{"url":"https://git.kernel.org/stable/c/8efbea0253b7fa2d1960cab0fed36544ca0b41ab"},{"url":"https://git.kernel.org/stable/c/f0e5c9c663badc9982e6941322eef1cb17de0f11"},{"url":"https://git.kernel.org/stable/c/18d8db24b0a5b7be4829238dd4022236df02d421"},{"url":"https://git.kernel.org/stable/c/1c9d0646a9959752f11ca1080dc1ff26bd1756cb"},{"url":"https://git.kernel.org/stable/c/69f030cf95488ae1186c72ac8c66fd279664ea7f"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code runs in ksmbd's in-kernel SMB server, reachable by remote attackers sending SMB2 CREATE requests over TCP port 445 after session establishment.\nAC:L - An authenticated attacker with share write access can plant a malformed parent security.NTACL xattr and reliably trigger the bug by creating a child file; they control both the crafted on-disk descriptor and the concurrent SMB request that exercises inheritance.\nPR:L - Exploitation requires an authenticated SMB2 session with write permission on the parent directory to create files; this is not a pre-authentication code path but does not require host root or special kernel capabilities.\nUI:N - Exploitation is fully automated over the SMB protocol and does not require any action from a separate victim user beyond normal server operation.\nS:U - The vulnerability is confined to the kernel's ksmbd security context and does not cross a VM, container, or IOMMU security boundary.\nC:H - The unchecked SID size computation and memcpy perform an out-of-bounds kernel heap read; stolen memory can be embedded in the newly created file's security descriptor and retrieved by the attacker.\nI:H - Unvalidated out-of-bounds memory access is a memory corruption primitive in kernel context; per kernel CVSS guidance, such bugs are scored at High integrity impact even when the immediate fault is a read.\nA:H - Reading from attacker-controlled out-of-bounds offsets can dereference unmapped or invalid kernel memory, causing an oops or panic and denying SMB service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:27:36.259Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.12.92"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}