CVE-2026-42007

Name	CVE-2026-42007
Description	An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing code, and to write memory contents beyond the intended buffer into the delivered mail. This causes memory leak and opportunity to do memory corruption during mail delivery, which can crash the delivery process and may allow execution of arbitrary code in the context of that process. Disable the Sieve editheader extension. Update to non-vulnerable version. 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-6526-1
Debian Bugs	1146018

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
dovecot (PTS)	bookworm, bookworm (security)	1:2.3.19.1+dfsg1-2.1+deb12u6	vulnerable
	trixie	1:2.4.1+dfsg1-6+deb13u6	vulnerable
	trixie (security)	1:2.4.1+dfsg1-6+deb13u7	fixed
	forky	1:2.4.5+dfsg1-2	fixed
	sid	1:2.4.5+dfsg1-3	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
dovecot	source	trixie	1:2.4.1+dfsg1-6+deb13u7		DSA-6526-1
dovecot	source	(unstable)	1:2.4.5+dfsg1-1			1146018

Notes

https://documentation.open-xchange.com/dovecot/security/advisories/html/2026/oxdc-adv-2026-0003.html#cve-2026-42007-sieve-editheader-rce
Fixed by: https://github.com/dovecot/pigeonhole/commit/69bac9cd6d4ac09100ee50c98052be1437f1da29
Fixed by: https://github.com/dovecot/pigeonhole/commit/cd9870e7f87e9d91e9d05b402da653df845b4f8f
Fixed by: https://github.com/dovecot/pigeonhole/commit/a44ba381619a06416ce3f34eae9765de46ece5d9