CVE-2026-77756: Apache Software Foundation Apache Tomcat

Low severity, CVSS 3.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat caused by processing the transfer-encoding header for an HTTP/1.0 request may allow an attacker to cause one request from another user to fail when Tomcat is located behind a reverse proxy. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.47 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.67 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

Affected products

• Apache Software Foundation Apache Tomcat: from 11.0.0-M1, up to and including 11.0.25; from 10.1.0-M1, up to and including 10.1.59; from 9.0.47, up to and including 9.0.121; from 8.5.67, up to and including 8.5.100

Published 2026-09-23. Last modified 2026-09-23.