What’s Vulnerable › Vulnerabilities

CVE-2026-34483: Apache Tomcat: Incomplete escaping of JSON access logs

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-09 · updated 2026-10-26
• Weakness: CWE-116

Description

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.

Affected products

• Apache Tomcat: from 9.0.40 before 9.0.117; from 10.1.0 before 10.1.54; from 11.0.0 before 11.0.21 — fixed in 9.0.117, 10.1.54, 11.0.21

How to fix

Upgrade to a fixed version: Apache Tomcat 9.0.117, 10.1.54, 11.0.21. Check the vendor advisory for mitigations.

References

• https://lists.apache.org/thread/j1w7304yonlr8vo1tkb5nfs7od1y228b
• http://www.openwall.com/lists/oss-security/2026/04/09/26

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