CVE-2025-23419: TLS Session Resumption Vulnerability
Last updated 24 February 2025
Other sources
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/ngxhttpsslmodule.html#sslsessionticketkey are used and/or the SSL session cache https://nginx.org/en/docs/http/ngxhttpsslmodule.html#sslsessioncache 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.
— NVD
When name-based virtual hosts are configured to share the same IP address and port combination, with TLS 1.3 and OpenSSL, a previously authenticated attacker can use session resumption to bypass client certificate authentication requirements on these servers. This vulnerability arises when TLS session tickets are used and/or the SSL session cache is used in the default virtual server and the default virtual server is performing client certificate authentication. This issue affects both the NGINX http and NGINX stream modules.
— F5
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/nginxto a version that resolves this vulnerability.Fixed in 1.18.0-6.1+deb11u4Fixed in 1.22.1-9+deb12u1Fixed in 1.26.3-2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 33 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.27.431.26.33 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.22.1-13 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 1.25.4-3 - Configuration
If the default server/default virtual server performs client certificate authentication, disable/avoid using TLS Session Tickets (ssl_session_ticket_key) and the SSL session cache (ssl_session_cache).
nginx http (ngx_http_ssl_module) and nginx stream ssl_session_ticket_key (TLS Session Tickets) / ssl_session_cache (SSL session cache) usage on the default server (default virtual server) = Do not use TLS Session Tickets and/or SSL session cache in the default server (default virtual server) when client certificate authentication is configured - Configuration
Do not configure multiple server blocks or name-based virtual hosts that share the same IP address and port combination when TLS 1.3 with OpenSSL session resumption can reach client certificate authentication bypass; separate them to prevent cross-server session resumption bypass.
nginx (virtual host configuration) shared IP:port for server blocks and session resumption behavior = Ensure separate IP address/port (or avoid sharing) when client certificate authentication is enabled
Event History
Frequently Asked Questions
What is the severity of CVE-2025-23419?
CVE-2025-23419 is considered a high severity vulnerability due to its potential to bypass client certificate authentication.
How do I fix CVE-2025-23419?
To mitigate CVE-2025-23419, update NGINX Plus to version 28 or NGINX Open Source to a version beyond 1.27.3.
What type of attack does CVE-2025-23419 enable?
CVE-2025-23419 allows an authenticated attacker to bypass client certificate authentication using session resumption.
Which software is affected by CVE-2025-23419?
CVE-2025-23419 affects NGINX Plus version 28 and NGINX Open Source versions between 1.11.4 and 1.27.3.
What configurations are impacted by CVE-2025-23419?
CVE-2025-23419 impacts servers with name-based virtual hosts sharing the same IP address and port using TLS 1.3.