CVE-2026-31708
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| sles | affected | | |
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | fixed | 7.0.3-1 |
| debian | sid | fixed | 7.0.3-1 |
| debian | trixie | fixed | 6.12.85-1 |
| linux-kernel | affected | 6.6.136 | |
| windows | affected | |
References
- https://git.kernel.org/stable/c/078fae8f50adebb903ccf2252b44391324571e78
- https://git.kernel.org/stable/c/85fd46ee26a11841c670449508025965f61ce131
- https://git.kernel.org/stable/c/a34d456934fe42e4da5d2cc07787bf418bee99c6
- https://git.kernel.org/stable/c/a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e
- https://git.kernel.org/stable/c/ac2f14e4705d020f04e806efa0d49ab8dc2b145f
- https://www.suse.com/security/cve/CVE-2026-31708.html
- https://security-tracker.debian.org/tracker/CVE-2026-31708
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-31708
CWEs
CWE-125
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.