CVE-2026-34483: Apache Tomcat Apache Tomcat Has An Improper Vulnerability

HIGH
Advisory Identifier: GHSA-rv64-5gf8-9qq8
Share
CVSS 7.5
CWE-116
Published
Advisory Summary

CVE-2026-34483 is a HIGH (CVSS 7.5) apache tomcat has an improper vulnerability (CWE-116: Improper Encoding or Escaping of Output) affecting Apache Tomcat libraries in the Maven ecosystem. The issue involves apache tomcat has an improper encoding or escaping of output vulnerability in the jsonaccesslogvalve. Remediation is available by upgrading affected packages to version 9.0.116, 10.1.54, 11.0.21.

CVE-2026-34483 at a Glance

CVE Identifier CVE-2026-34483
GHSA Identifier GHSA-rv64-5gf8-9qq8
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-116: Improper Encoding or Escaping of Output
Affected Product Apache Tomcat
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2026-34483

To remediate this vulnerability, upgrade all affected Apache Tomcat dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.apache.tomcat:tomcat-catalina fixed: 9.0.116 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>9.0.116</version>
</dependency>
org.apache.tomcat:tomcat-catalina fixed: 10.1.54 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>10.1.54</version>
</dependency>
org.apache.tomcat:tomcat-catalina fixed: 11.0.21 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-catalina</artifactId>
    <version>11.0.21</version>
</dependency>
org.apache.tomcat:tomcat fixed: 9.0.116 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>9.0.116</version>
</dependency>
org.apache.tomcat:tomcat fixed: 10.1.54 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>10.1.54</version>
</dependency>
org.apache.tomcat:tomcat fixed: 11.0.21 
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat</artifactId>
    <version>11.0.21</version>
</dependency>
org.apache.tomcat.embed:tomcat-embed-core fixed: 9.0.116 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>9.0.116</version>
</dependency>
org.apache.tomcat.embed:tomcat-embed-core fixed: 10.1.54 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>10.1.54</version>
</dependency>
org.apache.tomcat.embed:tomcat-embed-core fixed: 11.0.21 
<dependency>
    <groupId>org.apache.tomcat.embed</groupId>
    <artifactId>tomcat-embed-core</artifactId>
    <version>11.0.21</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.apache.tomcat

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-34483, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.apache.tomcat

Analyze the terminal output to locate any version of Apache Tomcat in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.0.116), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.apache.tomcat command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-116: Improper Encoding or Escaping of Output, where the product 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. In Apache Tomcat, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2026-34483 Affected Apache Tomcat Versions

9 component(s)
Fixed Versions:
9.0.11610.1.5411.0.21
Product / Package Ecosystem Affected Versions Fixed Version
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
≥ 9.0.40
< 9.0.116
9.0.116
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
≥ 10.1.0-M1
< 10.1.54
10.1.54
org.apache.tomcat:tomcat-catalina
maven/org.apache.tomcat/tomcat-catalina
Maven
≥ 11.0.0-M1
< 11.0.21
11.0.21
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 9.0.40
< 9.0.116
9.0.116
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 10.1.0-M1
< 10.1.54
10.1.54
org.apache.tomcat:tomcat
maven/org.apache.tomcat/tomcat
Maven
≥ 11.0.0-M1
< 11.0.21
11.0.21
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
≥ 9.0.40
< 9.0.116
9.0.116
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
≥ 10.1.0-M1
< 10.1.54
10.1.54
org.apache.tomcat.embed:tomcat-embed-core
maven/org.apache.tomcat.embed/tomcat-embed-core
Maven
≥ 11.0.0-M1
< 11.0.21
11.0.21

References

NVD — CVE-2026-34483 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-34483
Apache Tomcat Source Repository REPOSITORY
https://github.com/apache/tomcat
lists.apache.org/thread/j1w7304yonlr... WEB
https://lists.apache.org/thread/j1w7304yonlr8vo1tkb5nfs7od1y228b
Apache Tomcat Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/04/09/26

Frequently Asked Questions

What is CVE-2026-34483?
CVE-2026-34483 is a security vulnerability in Apache Tomcat involving Apache Tomcat has an Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve under CWE-116: Improper Encoding or Escaping of Output.
Which Apache Tomcat versions are affected?
Affected versions include releases prior to 9.0.116, 10.1.54, 11.0.21 across affected packages: org.apache.tomcat:tomcat-catalina, org.apache.tomcat:tomcat, org.apache.tomcat.embed:tomcat-embed-core.
What version fixes CVE-2026-34483?
Upgrading to 9.0.116, 10.1.54, 11.0.21 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tomcat-catalina affected?
Yes, org.apache.tomcat:tomcat-catalina is affected in releases prior to 9.0.116, 10.1.54, 11.0.21. Upgrade your dependency to 9.0.116, 10.1.54, 11.0.21 or later.
Is tomcat affected?
Yes, org.apache.tomcat:tomcat is affected in releases prior to 9.0.116, 10.1.54, 11.0.21. Upgrade your dependency to 9.0.116, 10.1.54, 11.0.21 or later.
What is the CVSS score of CVE-2026-34483?
CVE-2026-34483 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2026-34483?
CVE-2026-34483 is classified under CWE-116: Improper Encoding or Escaping of Output (The product 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.).
How can I check Maven dependencies for CVE-2026-34483?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.apache.tomcat'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rv64-5gf8-9qq8",
  "modified" : "2026-04-10T21:38:22Z",
  "published" : "2026-04-09T21:31:30Z",
  "aliases" : [ "CVE-2026-34483" ],
  "summary" : "Apache Tomcat has an Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve",
  "details" : "Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve component of Apache Tomcat.\n\nThis 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.\n\nUsers are recommended to upgrade to version 11.0.21, 10.1.54 or 9.0.117 , which fix the issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
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  } ],
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    },
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  } ],
  "references" : [ {
    "type" : "ADVISORY",
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  }, {
    "type" : "PACKAGE",
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    "url" : "https://lists.apache.org/thread/j1w7304yonlr8vo1tkb5nfs7od1y228b"
  }, {
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    "url" : "http://www.openwall.com/lists/oss-security/2026/04/09/26"
  } ],
  "database_specific" : {
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    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-10T21:38:21Z",
    "nvd_published_at" : "2026-04-09T20:16:24Z"
  }
}