CVE-2026-42006

Name	CVE-2026-42006
Description	An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.
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)
References	DSA-6313-1
Debian Bugs	1136444

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
dovecot (PTS)	bullseye	1:2.3.13+dfsg1-2+deb11u1	vulnerable
	bullseye (security)	1:2.3.13+dfsg1-2+deb11u3	vulnerable
	bookworm	1:2.3.19.1+dfsg1-2.1+deb12u5	vulnerable
	bookworm (security)	1:2.3.19.1+dfsg1-2.1+deb12u6	fixed
	trixie	1:2.4.1+dfsg1-6+deb13u5	vulnerable
	trixie (security)	1:2.4.1+dfsg1-6+deb13u6	fixed
	forky, sid	1:2.4.4+dfsg1-1	fixed

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

Package	Type	Release	Fixed Version	Origin	Debian Bugs
dovecot	source	bookworm	1:2.3.19.1+dfsg1-2.1+deb12u6	DSA-6313-1
dovecot	source	trixie	1:2.4.1+dfsg1-6+deb13u6	DSA-6313-1
dovecot	source	(unstable)	1:2.4.4+dfsg1-1		1136444

Notes

https://www.openwall.com/lists/oss-security/2026/05/12/6
Fixed by: https://github.com/dovecot/core/commit/da1438c76b797f055d4ad7f0eaa17e5e29ca31ee (2.4.4)