CVE-2026-123611

Name	CVE-2026-123611
Description	rustls before 0.23.46 contains a key exchange downgrade vulnerability that allows network attackers to poison the per-server-name key-exchange group record via an unauthenticated ServerHello. Attackers can answer one connection with a ServerHello selecting X25519, causing later ClientHellos to send only classical shares and lose post-quantum confidentiality.
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)
Debian Bugs	1151104

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
rust-rustls (PTS)	bookworm	0.20.8-4	vulnerable
	trixie	0.23.26+ds-1	vulnerable
	forky	0.23.45+ds-1	vulnerable
	sid	0.23.46+ds-1	fixed

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

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
rust-rustls	source	(unstable)	0.23.46+ds-1			1151104

https://rustsec.org/advisories/RUSTSEC-2026-0349.html
https://github.com/advisories/GHSA-w44r-93j7-qv28
https://github.com/rustls/rustls/pull/3355