CVE-2026-31704

Name	CVE-2026-31704
Description	In the Linux kernel, the following vulnerability has been resolved: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char )pndace + size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	bullseye	5.10.223-1	fixed
	bullseye (security)	5.10.251-5	fixed
	bookworm	6.1.170-3	vulnerable
	bookworm (security)	6.1.172-1	vulnerable
	trixie	6.12.86-1	fixed
	trixie (security)	6.12.88-1	fixed
	forky, sid	7.0.7-1	fixed

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

Package	Type	Release	Fixed Version
linux	source	bullseye	(not affected)
linux	source	trixie	6.12.85-1
linux	source	(unstable)	7.0.3-1

[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/299f962c0b02d048fb45d248b4da493d03f3175d (7.1-rc1)