CVE-2026-28753

Name	CVE-2026-28753
Description	NGINX Plus and NGINX Open Source have a vulnerability in the ngx_mail_smtp_module module due to the improper handling of CRLF sequences in DNS responses. This allows an attacker-controlled DNS server to inject arbitrary headers into SMTP upstream requests, leading to potential request manipulation. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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
nginx (PTS)	bullseye	1.18.0-6.1+deb11u3	vulnerable
	bullseye (security)	1.18.0-6.1+deb11u5	vulnerable
	bookworm	1.22.1-9+deb12u3	vulnerable
	bookworm (security)	1.22.1-9+deb12u4	vulnerable
	trixie (security), trixie	1.26.3-3+deb13u2	vulnerable
	forky, sid	1.28.3-2	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
nginx	source	(unstable)	1.28.3-1

Notes

[trixie] - nginx <no-dsa> (Minor issue)
[bookworm] - nginx <no-dsa> (Minor issue)
https://my.f5.com/manage/s/article/K000160367
Fixed by: https://github.com/nginx/nginx/commit/6a8513761fb327f67fcc6cfcf1ad216887e2589f (release-1.28.3)