smb: client: fix off-by-8 bounds check in check_wsl_eas()

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Summary

CVECVE-2026-31614
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-24 15:16:40 UTC
Updated2026-04-29 18:03:40 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: smb: client: fix off-by-8 bounds check in check_wsl_eas() The bounds check uses (u8 *)ea + nlen + 1 + vlen as the end of the EA name and value, but ea_data sits at offset sizeof(struct smb2_file_full_ea_info) = 8 from ea, not at offset 0. The strncmp() later reads ea->ea_data[0..nlen-1] and the value bytes follow at ea_data[nlen+1..nlen+vlen], so the actual end is ea->ea_data + nlen + 1 + vlen. Isn't pointer math fun? The earlier check (u8 *)ea > end - sizeof(*ea) only guarantees the 8-byte header is in bounds, but since the last EA is placed within 8 bytes of the end of the response, the name and value bytes are read past the end of iov. Fix this mess all up by using ea->ea_data as the base for the bounds check. An "untrusted" server can use this to leak up to 8 bytes of kernel heap into the EA name comparison and influence which WSL xattr the data is interpreted as.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

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

EPSS: 0.000180000 probability, percentile 0.048130000 (date 2026-04-27)

Problem Types: CWE-125

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 7449d736bbbd160c76b01b8fcdf72f58a8757d4b bfbc74df8bbe095b3ed68f6d4487b368af087890 git Not specified
CNA Linux Linux affected ea41367b2a602f602ea6594fc4a310520dcc64f4 5cc0574c84aa73946ade587c41e81757b8b01cb5 git Not specified
CNA Linux Linux affected ea41367b2a602f602ea6594fc4a310520dcc64f4 b2b76d09a64c538c57006180103fc1841e8cfa66 git Not specified
CNA Linux Linux affected ea41367b2a602f602ea6594fc4a310520dcc64f4 ba3ad159aa61810bbe0acaf39578b1ebfb6f1a18 git Not specified
CNA Linux Linux affected ea41367b2a602f602ea6594fc4a310520dcc64f4 a893f1757d9a4009e4a8d7ceb2312142fe29cea4 git Not specified
CNA Linux Linux affected ea41367b2a602f602ea6594fc4a310520dcc64f4 3d8b9d06bd3ac4c6846f5498800b0f5f8062e53b git Not specified
CNA Linux Linux affected 6.9 Not specified
CNA Linux Linux unaffected 6.9 semver Not specified
CNA Linux Linux unaffected 6.6.136 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.83 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.24 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.14 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0.1 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/3d8b9d06bd3ac4c6846f5498800b0f5f8062e53b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5cc0574c84aa73946ade587c41e81757b8b01cb5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/bfbc74df8bbe095b3ed68f6d4487b368af087890 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/ba3ad159aa61810bbe0acaf39578b1ebfb6f1a18 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/a893f1757d9a4009e4a8d7ceb2312142fe29cea4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/b2b76d09a64c538c57006180103fc1841e8cfa66 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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