In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix OOB read/write from unvalidated DataOffset in coalesce_t2()
coalesce_t2() computes data pointers directly from server-supplied
DataOffset fields with no validation against buffer bounds:
data_area_of_tgt = (char *)&pSMBt->hdr.Protocol +
get_unaligned_le16(&pSMBt->t2_rsp.DataOffset);
data_area_of_src = (char *)&pSMBs->hdr.Protocol +
get_unaligned_le16(&pSMBs->t2_rsp.DataOffset);
data_area_of_tgt += total_in_tgt;
...
memcpy(data_area_of_tgt, data_area_of_src, total_in_src);
A small DataOffset can push a pointer below the actual byte area,
overwriting header fields; a large one can push it past the buffer
end, causing out-of-bounds heap reads (source) or writes (target).
The BCC overflow guard does not prevent this: BCC reflects how much
data is present, while DataOffset controls where in the buffer it
starts.
The "validate target area" comment present since the function was
first written in 2005 was a placeholder that was never implemented.
Add lower- and upper-bound checks for both data pointers before the
memcpy, and before any target header fields are modified.
References
Configurations
No configuration.
History
No history.
Information
Published : 2026-09-11 20:19
Updated : 2026-09-13 07:17
NVD link : CVE-2026-89633
Mitre link : CVE-2026-89633
CVE.ORG link : CVE-2026-89633
JSON object : View
Products Affected
No product.
CWE
No CWE.