smb: client: harden POSIX SID length parsing

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64380
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:21 UTC
Updated2026-07-27 05:16:44 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: smb: client: harden POSIX SID length parsing posix_info_sid_size() reads sid[1] to obtain the subauthority count, but its existing boundary check still accepts buffers with only one remaining byte. Require two bytes before reading sid[1] so all client paths that reuse the helper reject truncated POSIX SIDs safely.

Risk And Classification

Primary CVSS: v3.1 8.2 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS: 0.004430000 probability, percentile 0.363080000 (date 2026-07-28)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
3.1CNADECLARED8.2HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 171605aed68380c2fa75dff9b3a1ed427c50065b git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 4213c1208978483021d7d125c131de3985d38f61 git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 96e889bc1e759c83f25093e8c2f3da31b4973f30 git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 0de5b8e76847f5de26f364a82c6602c4881c30da git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 427eb7eb46425fec845a43e861f3d6e2899cae59 git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 86c5d470f5d42e61123b2f4b4f0b91f4eee5b980 git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 46a84715a015cb48e1b9c219dc88c03d8a541ea4 git Not specified
CNA Linux Linux affected 349e13ad30b45998bb9937cfe0b32be6f951976d 7ad2bcf2441430bb2e918fb3ef9a90d775a6e422 git Not specified
CNA Linux Linux affected 5.7 Not specified
CNA Linux Linux unaffected 5.7 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/171605aed68380c2fa75dff9b3a1ed427c50065b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/427eb7eb46425fec845a43e861f3d6e2899cae59 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/96e889bc1e759c83f25093e8c2f3da31b4973f30 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/86c5d470f5d42e61123b2f4b4f0b91f4eee5b980 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4213c1208978483021d7d125c131de3985d38f61 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0de5b8e76847f5de26f364a82c6602c4881c30da 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7ad2bcf2441430bb2e918fb3ef9a90d775a6e422 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/46a84715a015cb48e1b9c219dc88c03d8a541ea4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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