Improper Output Encoding in Apache Tomcat Affects Multiple Versions
CVE-2026-34483

7.5HIGH

Key Information:

Vendor

Apache
Status
Apache Tomcat
Vendor
CVE Published:
9 April 2026

What is CVE-2026-34483?

An improper encoding or escaping of output vulnerability exists in the JsonAccessLogValve component of Apache Tomcat, which can potentially allow attackers to manipulate logged data. This flaw affects specific versions of Apache Tomcat from 11.0.0-M1 through 11.0.20, 10.1.0-M1 through 10.1.53, and 9.0.40 through 9.0.116. Users are encouraged to upgrade to versions 11.0.21, 10.1.54, or 9.0.117 to mitigate the risk.

Affected Version(s)

Apache Tomcat 11.0.0-M1 <= 11.0.20

Apache Tomcat 10.1.0-M1 <= 10.1.53

Apache Tomcat 9.0.40 <= 9.0.116

References

https://lists.apache.org/thread/j1w7304yonlr8vo1tkb5nfs7o...
vendor-advisory

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Bartlomiej Dmitruk, striga.ai
.