GHSA-rv64-5gf8-9qq8 BIT-tomcat-2026-34483 CVE-2026-34483
Apache Tomcat has an Improper Encoding or Escaping of Output vulnerability in the JsonAccessLogValve
High
Maven
- Severity
- 7.5 / 10
- High · CVSS 3.1
- Exploit chance (EPSS)
- 0.46%
- Chance of exploitation in the next 30 days. Higher than 39.99% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-116 Improper Encoding or Escaping of Output
- Fix
- Available
- 3 packages have a fixed version
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 versions
Maven
| Package | Vulnerable | Fixed in |
|---|---|---|
| org.apache.tomcat.embed:tomcat-embed-core | >= 9.0.40, < 9.0.116 |
9.0.116 |
| org.apache.tomcat.embed:tomcat-embed-core | >= 10.1.0-M1, < 10.1.54 |
10.1.54 |
| org.apache.tomcat.embed:tomcat-embed-core | >= 11.0.0-M1, < 11.0.21 |
11.0.21 |
| org.apache.tomcat:tomcat | >= 9.0.40, < 9.0.116 |
9.0.116 |
| org.apache.tomcat:tomcat | >= 10.1.0-M1, < 10.1.54 |
10.1.54 |
| org.apache.tomcat:tomcat | >= 11.0.0-M1, < 11.0.21 |
11.0.21 |
| org.apache.tomcat:tomcat-catalina | >= 9.0.40, < 9.0.116 |
9.0.116 |
| org.apache.tomcat:tomcat-catalina | >= 10.1.0-M1, < 10.1.54 |
10.1.54 |
| org.apache.tomcat:tomcat-catalina | >= 11.0.0-M1, < 11.0.21 |
11.0.21 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
org.apache.tomcat.embed:tomcat-embed-core Maven → 9.0.116
- maven
<dependency><groupId>org.apache.tomcat.embed</groupId><artifactId>tomcat-embed-core</artifactId><version>9.0.116</version></dependency>- gradle
implementation("org.apache.tomcat.embed:tomcat-embed-core:9.0.116")
org.apache.tomcat:tomcat Maven → 9.0.116
- maven
<dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat</artifactId><version>9.0.116</version></dependency>- gradle
implementation("org.apache.tomcat:tomcat:9.0.116")
org.apache.tomcat:tomcat-catalina Maven → 9.0.116
- maven
<dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat-catalina</artifactId><version>9.0.116</version></dependency>- gradle
implementation("org.apache.tomcat:tomcat-catalina:9.0.116")
Severity breakdown
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
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 to prevent it
- Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error. Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
- Architecture and Design: If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated. For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
- Architecture and Design, Implementation: Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
- Architecture and Design: In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
- Architecture and Design: Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
- Requirements: Fully specify which encodings are required by components that will be communicating with each other.
- Implementation: When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-69r9-qgr7-g2wj Apache Tomcat Missing Encryption of Sensitive Data vulnerability | High Known exploited | Also affects org.apache.tomcat:tomcat |
| GHSA-83qj-6fr2-vhqg Apache Tomcat: Potential RCE and/or information disclosure and/or information corruption with partial PUT | Critical Known exploited | Also affects org.apache.tomcat.embed:tomcat-embed-core |
| GHSA-qppj-fm5r-hxr3 HTTP/2 Stream Cancellation Attack | Medium Known exploited | Also affects org.apache.tomcat.embed:tomcat-embed-core |
| GHSA-xjgh-84hx-56c5 Unrestricted Upload of File with Dangerous Type Apache Tomcat | High Known exploited | Also affects org.apache.tomcat.embed:tomcat-embed-core |
| GHSA-cw54-59pw-4g8c Apache Tomcat Improper Access Control vulnerability | Critical Known exploited | Also affects org.apache.tomcat:tomcat-catalina |
| CVE-2020-1938 Improper Privilege Management in Tomcat | Critical Known exploited | Also affects org.apache.tomcat.embed:tomcat-embed-core |
| GHSA-pjfr-qf3p-3q25 When running Apache Tomcat on Windows with HTTP PUTs enabled it was possible to upload a JSP file to the server | High Known exploited | Also affects org.apache.tomcat.embed:tomcat-embed-core |
| GHSA-h3x4-894j-xpx5 Apache Tomcat's FORM authentication process has an Incorrect Authorization vulnerability | Critical | Also affects org.apache.tomcat.embed:tomcat-embed-core |
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