Apache Tomcat IERSS Bypass in Rewrite Rules (V8–11.x)
CVE-2025-31651 Published on April 28, 2025
Apache Tomcat: Bypass of rules in Rewrite Valve
Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in Apache Tomcat. For a subset of unlikely rewrite rule configurations, it was possible
for a specially crafted request to bypass some rewrite rules. If those
rewrite rules effectively enforced security constraints, those
constraints could be bypassed.
This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.5, from 10.1.0-M1 through 10.1.39, from 9.0.0.M1 through 9.0.102.
The following versions were EOL at the time the CVE was created but are
known to be affected: 8.5.0 though 8.5.100. Other, older, EOL versions
may also be affected.
Users are recommended to upgrade to version [FIXED_VERSION], which fixes the issue.
Vulnerability Analysis
CVE-2025-31651 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 be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.
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-2025-31651 has been classified to as an Output Sanitization vulnerability or weakness.
Products Associated with CVE-2025-31651
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Affected Versions
Apache Software Foundation Apache Tomcat:- Version 11.0.0-M1, <= 11.0.5 is affected.
- Version 10.1.0-M1, <= 10.1.39 is affected.
- Version 9.0.0.M1, <= 9.0.102 is affected.
- Version 8.5.0, <= 8.5.100 is affected.
- Version 8.0.0.RC1 and below 8.5.0 is unknown.
- Version 10.0.0-M1, <= 10.0.27 is unknown.
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.