smb: client: restore the data_offset bound in is_valid_oplock_break()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89630
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:48 UTC
Updated2026-10-19 09:17:59 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: smb: client: restore the data_offset bound in is_valid_oplock_break() Commit 83bfbd0bb902 ("cifs: Remove the RFC1002 header from smb_hdr") changed the quantity this bound is measured against. It used to be srv->total_read minus the 4-byte RFC1002 preamble that total_read then included, so it was the SMB message length. The same commit stopped counting the preamble, and the mechanical substitution to srv->total_read - srv->pdu_size left an expression that is identically zero: standard_receive3() reads MID_HEADER_SIZE() bytes and then exactly pdu_length - MID_HEADER_SIZE() more, adding both to total_read. len is therefore 0, the subtraction below it wraps, and no __u32 DataOffset can exceed the result, so the check from commit 097f5863b1a0 ("cifs: read overflow in is_valid_oplock_break()") no longer rejects anything. Use total_read, which is now the message length on its own.

Risk And Classification

Primary CVSS: v3.1 9.1 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.005390000 probability, percentile 0.437030000 (date 2026-10-12)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
3.1CNADECLARED9.1CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 83bfbd0bb9025f98fa62b44f93bd67466773d1db 5b16a1967a01ad4496a7206a87c3eb16f1df2b05 git Not specified
CNA Linux Linux affected 83bfbd0bb9025f98fa62b44f93bd67466773d1db ba22f575de9deeae4ae0859ca4315a7698226237 git Not specified
CNA Linux Linux affected 78e718c5aa146063cd70d2cc68297c3ac41f31ee git Not specified
CNA Linux Linux affected 6.18.56 6.19 semver Not specified
CNA Linux Linux affected 6.19 Not specified
CNA Linux Linux unaffected 6.19 semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ba22f575de9deeae4ae0859ca4315a7698226237 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5b16a1967a01ad4496a7206a87c3eb16f1df2b05 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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