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CVE-2026-31708

Published: May 2, 2026Last modified: June 24, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path smb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL and the default QUERY_INFO path. The QUERY_INFO branch clamps qi.input_buffer_length to the server-reported OutputBufferLength and then copies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but it never verifies that the flexible-array payload actually fits within rsp_iov[1].iov_len. A malicious server can return OutputBufferLength larger than the actual QUERY_INFO response, causing copy_to_user() to walk past the response buffer and expose adjacent kernel heap to userspace. Guard the QUERY_INFO copy with a bounds check on the actual Buffer payload. Use struct_size(qi_rsp, Buffer, qi.input_buffer_length) rather than an open-coded addition so the guard cannot overflow on 32-bit builds.

Severity score breakdown

ParameterValue
Base score8.1
Attack VectorNETWORK
Attack complexityLOW
Privileges requiredNONE
User interactionREQUIRED
ScopeUNCHANGED
ConfidentialityHIGH
Integrity impactNONE
Availability impactHIGH
VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

Status

ProductReleasePackageStatus
Alpaquita Linux23 LTSlinux-ltsFixed (6.1.175-r0)
25 LTSlinux-ltsFixed (6.12.85-r0)
Streamlinux-ltsFixed (6.18.35-r1)

References

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