CVE-2026-31432

Published: April 25, 2026Last modified: May 25, 2026

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix OOB write in QUERY_INFO for compound requests When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor. The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs. This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.

Severity score breakdown

Status

References

• https://git.kernel.org/stable/c/075ea208c648cc2bcd616295b711d3637c61de45
• https://git.kernel.org/stable/c/515c2daab46021221bdf406bef19bc90a44ec617
• https://git.kernel.org/stable/c/d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09
• https://git.kernel.org/stable/c/fda9522ed6afaec45cabc198d8492270c394c7bc