Apache Tomcat JsonAccessLogValve Encoding/escape Vulnerability (v9-10-11)
CVE-2026-34483 Published on April 9, 2026
Apache Tomcat: Incomplete escaping of JSON access logs
Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve component of Apache Tomcat.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.20, from 10.1.0-M1 through 10.1.53, from 9.0.40 through 9.0.116.
Users are recommended to upgrade to version 11.0.21, 10.1.54 or 9.0.117 , which fix the issue.
Vulnerability Analysis
CVE-2026-34483 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
What is an Output Sanitization Vulnerability?
The software prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
CVE-2026-34483 has been classified to as an Output Sanitization vulnerability or weakness.
Products Associated with CVE-2026-34483
Want to know whenever a new CVE is published for Apache Tomcat? stack.watch will email you.
Affected Versions
Apache Software Foundation Apache Tomcat:- Version 11.0.0-M1, <= 11.0.20 is affected.
- Version 10.1.0-M1, <= 10.1.53 is affected.
- Version 9.0.40, <= 9.0.116 is affected.
- Version 8.5.84, <= 8.5.100 is affected.
- Before and including 8.5.83 is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.