CVE-2025-23419

Name	CVE-2025-23419
Description	When multiple server blocks are configured to share the same IP address and port, an attacker can use session resumption to bypass client certificate authentication requirements on these servers. This vulnerability arises when TLS Session Tickets https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_ticket_key are used and/or the SSL session cache https://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_session_cache are used in the default server and the default server is performing client certificate authentication. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1095403

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nginx (PTS)	bullseye (security), bullseye	1.18.0-6.1+deb11u3	vulnerable
	bookworm	1.22.1-9	vulnerable
	trixie	1.26.0-3	vulnerable
	sid	1.26.3-2	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)	1.26.3-2			1095403

Notes

https://www.openwall.com/lists/oss-security/2025/02/05/8
https://github.com/nginx/nginx/commit/13935cf9fdc3c8d8278c70716417d3b71c36140e (release-1.26.3)