Improper Encoding or Escaping of Output in Apache Tomcat - CVE-2026-34483
Published: April 9, 2026 / Updated: April 10, 2026
Vulnerability identifier: #VU125747
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-34483
CWE-ID: CWE-116
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Apache Foundation
Affected software:
Apache Tomcat
Apache Tomcat
Detailed vulnerability description
The vulnerability allows a remote attacker to inject arbitrary JSON into the JSON access log.
The vulnerability exists due to incomplete escaping in the JSON access log when handling requests with non-default Connector attributes relaxedPathChars and/or relaxedQueryChars. A remote attacker can send a specially crafted request to inject arbitrary JSON into the JSON access log.
Only configurations using non-default values for relaxedPathChars and/or relaxedQueryChars are affected.
How to mitigate CVE-2026-34483
Install security update from vendor's website.