{"id":"CVE-2026-64380","state":"PUBLISHED","title":"smb: client: harden POSIX SID length parsing","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: harden POSIX SID length parsing\n\nposix_info_sid_size() reads sid[1] to obtain the subauthority count,\nbut its existing boundary check still accepts buffers with only one\nremaining byte. Require two bytes before reading sid[1] so all client\npaths that reuse the helper reject truncated POSIX SIDs safely.","publishedAt":"2026-07-25T08:50:30.476Z","updatedAt":"2026-10-19T20:38:25.851Z","severity":{"score":8.2,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"171605aed68380c2fa75dff9b3a1ed427c50065b","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"4213c1208978483021d7d125c131de3985d38f61","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"96e889bc1e759c83f25093e8c2f3da31b4973f30","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"0de5b8e76847f5de26f364a82c6602c4881c30da","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"427eb7eb46425fec845a43e861f3d6e2899cae59","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"86c5d470f5d42e61123b2f4b4f0b91f4eee5b980","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"46a84715a015cb48e1b9c219dc88c03d8a541ea4","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"7ad2bcf2441430bb2e918fb3ef9a90d775a6e422","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]}],"references":["https://git.kernel.org/stable/c/171605aed68380c2fa75dff9b3a1ed427c50065b","https://git.kernel.org/stable/c/4213c1208978483021d7d125c131de3985d38f61","https://git.kernel.org/stable/c/96e889bc1e759c83f25093e8c2f3da31b4973f30","https://git.kernel.org/stable/c/0de5b8e76847f5de26f364a82c6602c4881c30da","https://git.kernel.org/stable/c/427eb7eb46425fec845a43e861f3d6e2899cae59","https://git.kernel.org/stable/c/86c5d470f5d42e61123b2f4b4f0b91f4eee5b980","https://git.kernel.org/stable/c/46a84715a015cb48e1b9c219dc88c03d8a541ea4","https://git.kernel.org/stable/c/7ad2bcf2441430bb2e918fb3ef9a90d775a6e422"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64380.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64380","state":"PUBLISHED","datePublished":"2026-07-25T08:50:30.476Z","dateUpdated":"2026-10-19T20:38:25.851Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.784Z"},"containers":{"cna":{"title":"smb: client: harden POSIX SID length parsing","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: harden POSIX SID length parsing\n\nposix_info_sid_size() reads sid[1] to obtain the subauthority count,\nbut its existing boundary check still accepts buffers with only one\nremaining byte. Require two bytes before reading sid[1] so all client\npaths that reuse the helper reject truncated POSIX SIDs safely."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"171605aed68380c2fa75dff9b3a1ed427c50065b","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"4213c1208978483021d7d125c131de3985d38f61","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"96e889bc1e759c83f25093e8c2f3da31b4973f30","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"0de5b8e76847f5de26f364a82c6602c4881c30da","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"427eb7eb46425fec845a43e861f3d6e2899cae59","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"86c5d470f5d42e61123b2f4b4f0b91f4eee5b980","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"46a84715a015cb48e1b9c219dc88c03d8a541ea4","versionType":"git"},{"version":"349e13ad30b45998bb9937cfe0b32be6f951976d","status":"affected","lessThan":"7ad2bcf2441430bb2e918fb3ef9a90d775a6e422","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.7","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.7","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smb2pdu.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/171605aed68380c2fa75dff9b3a1ed427c50065b"},{"url":"https://git.kernel.org/stable/c/4213c1208978483021d7d125c131de3985d38f61"},{"url":"https://git.kernel.org/stable/c/96e889bc1e759c83f25093e8c2f3da31b4973f30"},{"url":"https://git.kernel.org/stable/c/0de5b8e76847f5de26f364a82c6602c4881c30da"},{"url":"https://git.kernel.org/stable/c/427eb7eb46425fec845a43e861f3d6e2899cae59"},{"url":"https://git.kernel.org/stable/c/86c5d470f5d42e61123b2f4b4f0b91f4eee5b980"},{"url":"https://git.kernel.org/stable/c/46a84715a015cb48e1b9c219dc88c03d8a541ea4"},{"url":"https://git.kernel.org/stable/c/7ad2bcf2441430bb2e918fb3ef9a90d775a6e422"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","baseScore":8.2,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - A malicious SMB server can deliver the truncated POSIX SID through SMB3.1.1 query-info or query-directory responses over TCP.\nAC:L - The server directly controls the response length and can deterministically leave exactly one SID byte remaining; no race or uncontrollable condition is required.\nPR:N - The malicious server needs no privileges on the vulnerable client, and guest-capable or attacker-controlled shares can supply the response after connection establishment.\nUI:N - On an already mounted POSIX-enabled share, routine automated stat, readdir, or metadata operations can trigger parsing without human interaction.\nS:U - The out-of-bounds access occurs within the client kernel and does not cross a virtualization, IOMMU, or other separate security authority boundary.\nC:L - The primitive reads exactly one byte beyond the response boundary, limiting any confidentiality effect to adjacent memory rather than providing an arbitrary-read primitive.\nI:N - The out-of-bounds byte only influences validation, which always rejects because a legal SID requires at least 12 bytes; no attacker-influenced copy or memory write follows.\nA:H - The server can place the truncated SID at the receive allocation boundary, where the out-of-bounds access can trigger a sanitizer fault or kernel oops and can be repeated to crash the client."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:54:31.740Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64380","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:39:47.266663Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","type":"CWE","description":"CWE-125 Out-of-bounds Read"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:38:25.851Z"}}]}}}