ksmbd: do not expire session on binding failure

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Summary

CVECVE-2026-31476
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-22 14:16:44 UTC
Updated2026-06-01 17:16:47 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ksmbd: do not expire session on binding failure When a multichannel session binding request fails (e.g. wrong password), the error path unconditionally sets sess->state = SMB2_SESSION_EXPIRED. However, during binding, sess points to the target session looked up via ksmbd_session_lookup_slowpath() -- which belongs to another connection's user. This allows a remote attacker to invalidate any active session by simply sending a binding request with a wrong password (DoS). Fix this by skipping session expiration when the failed request was a binding attempt, since the session does not belong to the current connection. The reference taken by ksmbd_session_lookup_slowpath() is still correctly released via ksmbd_user_session_put().

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:N/I:L/A:H

EPSS: 0.000760000 probability, percentile 0.225440000 (date 2026-04-27)

Problem Types: NVD-CWE-noinfo

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

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff 4642ea35c03cf3d3558c009df4757cdb7af3f82d git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff f5300690c23c5ac860499bb37dbc09cf43fd62e6 git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff 6fafc4c4238e538969f1375f9ecdc6587c53f1cc git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff 1d1888b4a7aec518b707f6eca0bf08992c0e8da3 git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff a897064a457056acb976e20e3007cdf553de340f git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff e0e5edc81b241c70355217de7e120c97c3429deb git Not specified
CNA Linux Linux affected f5a544e3bab78142207e0242d22442db85ba1eff 9bbb19d21ded7d78645506f20d8c44895e3d0fb9 git Not specified
CNA Linux Linux affected 5.15 Not specified
CNA Linux Linux unaffected 5.15 semver Not specified
CNA Linux Linux unaffected 5.15.209 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.131 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.80 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.21 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.11 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a897064a457056acb976e20e3007cdf553de340f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/e0e5edc81b241c70355217de7e120c97c3429deb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/4642ea35c03cf3d3558c009df4757cdb7af3f82d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6fafc4c4238e538969f1375f9ecdc6587c53f1cc 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1d1888b4a7aec518b707f6eca0bf08992c0e8da3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/9bbb19d21ded7d78645506f20d8c44895e3d0fb9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f5300690c23c5ac860499bb37dbc09cf43fd62e6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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