Executive brief
Apache Tomcat is a widely used web server and application container for Java-based websites. A vulnerability was identified where the server fails to respect the security administrator's preferred order of encryption methods (ciphers). This could allow a connection to use a weaker encryption method than intended, potentially exposing sensitive data to interception.
Technical details
A vulnerability in Apache Tomcat (CWE-327) occurs because the server does not preserve the configured cipher preference order during the TLS handshake. This issue affects Tomcat versions 11.0.16-11.0.18, 10.1.51-10.1.52, and 9.0.114-9.0.115. An unauthenticated remote attacker can exploit this by negotiating a connection using a weaker cipher than the administrator intended, even if stronger ciphers are available and prioritized in the configuration. This can lead to a loss of confidentiality if the negotiated cipher is susceptible to known cryptographic attacks. The issue is resolved in versions 11.0.20, 10.1.53, and 9.0.116.
Affected products
- Apache Tomcat 9.0.114 to 9.0.115, 10.1.51 to 10.1.52, 11.0.16 to 11.0.18
Timeline
- 2026-04-09: disclosed
- 2026-04-09: advisory
- 2026-04-10: other: GitHub advisory reviewed