CVE-2026-40684

Name	CVE-2026-40684
Description	In Exim before 4.99.2, on systems using musl libc (not glibc), an attacker can crash the connection instance when malformed DNS data is present in PTR records. This is caused by a dn_expand oddity in octal printing.
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
exim4 (PTS)	bullseye	4.94.2-7+deb11u3	vulnerable
	bullseye (security)	4.94.2-7+deb11u4	vulnerable
	bookworm, bookworm (security)	4.96-15+deb12u7	vulnerable
	trixie	4.98.2-1	vulnerable
	forky, sid	4.99.2-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
exim4	source	(unstable)	4.99.2-1	unimportant

Fixed by: https://code.exim.org/exim/exim/commit/628bbaca7672748d941a12e7cd5f0122a4e18c81
Debian builds with glibc