Apache WSS4J <=4.0.2 XPath Validator Bypass permitting unsigned SOAP
CVE-2026-87830 Published on September 30, 2026
Apache WSS4J: Streaming WS-SecurityPolicy validation may skip element-protection checks.
In the StAX streaming WS-SecurityPolicy validator, certain relative or unsupported XPath expressions can be converted into paths that never match the actual XML element path. A remote SOAP peer may therefore send a required element without the expected signature or encryption.
Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.
Vulnerability Analysis
CVE-2026-87830 is exploitable 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 have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is an EL Injection Vulnerability?
The software constructs all or part of an expression language (EL) statement in a Java Server Page (JSP) using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended EL statement before it is executed.
CVE-2026-87830 has been classified to as an EL Injection vulnerability or weakness.
Products Associated with CVE-2026-87830
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Affected Versions
Apache Software Foundation Apache WSS4J:- Version 4.0.0 and below 4.0.2 is affected.
- Version 3.0.0 and below 3.0.6 is affected.
- Before 2.4.4 is affected.