CVE-2026-31432

NameCVE-2026-31432
DescriptionIn 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-6238-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)bullseye5.10.223-1fixed
bullseye (security)5.10.251-4fixed
bookworm6.1.159-1vulnerable
bookworm (security)6.1.170-3vulnerable
trixie6.12.73-1vulnerable
trixie (security)6.12.86-1fixed
forky, sid7.0.4-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebullseye(not affected)
linuxsourcetrixie6.12.85-1DSA-6238-1
linuxsource(unstable)6.19.12-1

Notes

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/fda9522ed6afaec45cabc198d8492270c394c7bc (7.0-rc7)

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