CVE-2026-34483 Apache Tomcat - Incomplete escaping of JSON access logs
Severity: Low
Vendor: The Apache Software Foundation
Versions Affected:
Apache Tomcat 11.0.0-M1 to 11.0.20
Apache Tomcat 10.1.0-M1 to 10.1.53
Apache Tomcat 9.0.40 to 9.0.116
Older, EOS versions may also be affected
Description:
Incomplete escaping when non-default values were used for the Connector
attributes relaxedPathChars and/or relaxedQueryChars allowed the
injection of arbitrary JSON into the JSON access log.
Mitigation:
Users of the affected versions should apply one of the following
mitigations:
- Upgrade to Apache Tomcat 11.0.21 or later
- Upgrade to Apache Tomcat 10.1.54 or later
- Upgrade to Apache Tomcat 9.0.117 or later
Credit:
This issue was identified by Bartlomiej Dmitruk, striga.ai
History:
2026-04-09 Original advisory
References:
[1] https://tomcat.apache.org/security-11.html
[2] https://tomcat.apache.org/security-10.html
[3] https://tomcat.apache.org/security-9.html
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