CVE-2009-0580: Apache Tomcat

Medium severity, CVSS 4.3. EPSS: 94.4% chance of exploitation in the next 30 days.

Apache Tomcat 4.1.0 through 4.1.39, 5.5.0 through 5.5.27, and 6.0.0 through 6.0.18, when FORM authentication is used, allows remote attackers to enumerate valid usernames via requests to /j_security_check with malformed URL encoding of passwords, related to improper error checking in the (1) MemoryRealm, (2) DataSourceRealm, and (3) JDBCRealm authentication realms, as demonstrated by a % (percent) value for the j_password parameter.

Affected products

• Apache Tomcat: version 4.1.0 only; version 4.1.1 only; version 4.1.2 only; version 4.1.3 only; version 4.1.4 only; version 4.1.5 only; …

Published 2009-06-05. Last modified 2026-06-16.