CVE-2026-100227 in CXF
Summary
by MITRE • 10/09/2026
Improper Verification of Cryptographic Signature vulnerability in Apache CXF's JAX-RS XML Security module. The JAX-RS XML Signature interceptors (XmlSigInHandler, XmlSigInInterceptor and the streaming XmlSecInInterceptor) did not ensure that the XML passed to the application was covered by the signature. An attacker with any document signed by a trusted key could wrap it in unsigned content, which the application would then treat as signed. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.
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Analysis
by VulDB Data Team • 10/09/2026
The vulnerability identified within Apache CXF's JAX-RS XML Security module represents a critical failure in the verification of cryptographic signatures, specifically affecting the XmlSigInHandler, XmlSigInInterceptor, and the streaming XmlSecInInterceptor components. This flaw stems from an improper validation mechanism where the system fails to ensure that the entire payload received by the application is covered by the digital signature provided with it. In a secure implementation, any modification or wrapping of signed content should result in signature verification failure because the hash would no longer match the original data. However, due to this specific logic error, an attacker can exploit the parsing behavior to embed unsigned XML fragments around or within the legitimately signed document. The application processes these components and ultimately treats the combined structure as authentic and unaltered, effectively bypassing the integrity guarantees that digital signatures are designed to provide.
From a technical perspective, this issue allows for what is known as an XML signature wrapping attack. By leveraging the flexibility of XML parsing, an adversary can take any document that has been signed with a trusted key and wrap it in additional unsigned content. The vulnerable interceptors do not strictly validate that the root element or all relevant parts of the incoming message are encompassed by the reference within the signature block. Consequently, the application accepts the wrapped payload as valid because the inner portion matches the expected hash, ignoring the surrounding unsigned data which may contain malicious instructions or altered parameters. This undermines the core security principles of integrity and authenticity, allowing attackers to inject arbitrary commands or modify business logic without triggering a cryptographic error that would normally halt processing.
The operational impact of this vulnerability is severe for any enterprise application relying on Apache CXF for secure web service communication via JAX-RS with XML signatures. Attackers who can intercept network traffic or manipulate input data can perform unauthorized actions by injecting unsigned content into signed requests. This could lead to privilege escalation, where an attacker modifies request parameters that are not covered by the signature but affect application behavior after parsing. It also facilitates data integrity violations, allowing sensitive information to be altered in transit without detection. Since this affects both standard and streaming interceptors, systems processing large payloads or high-throughput services remain vulnerable unless explicitly patched. The ability to bypass signature verification effectively nullifies non-repudiation guarantees, making it difficult for organizations to prove the origin of specific transactions if such attacks are successfully executed.
This vulnerability aligns with CWE-345, which describes Insufficient Verification of Data Authenticity, and specifically relates to improper handling of XML structures that leads to signature bypasses similar to those categorized under CWE-611, Improper Restriction of XML External Entity Reference or related parsing flaws when combined with wrapping techniques. In the context of the MITRE ATT&CK framework, this flaw facilitates tactics associated with Defense Evasion and Command and Control, as attackers can disguise malicious payloads within seemingly legitimate signed communications to bypass security controls that rely on signature validation for trust decisions. The exploitation does not require breaking the cryptographic algorithm itself but rather exploits a logical gap in how the application validates the scope of the signed data relative to the received message structure.
To mitigate this risk, organizations must immediately upgrade Apache CXF to version 4.2.4, 4.1.9, or 3.6.13, as these releases contain patches that enforce strict validation of XML signature coverage. These updates ensure that all parts of the incoming document are verified against the provided cryptographic signatures before being processed by the application logic. In addition to upgrading software, security teams should implement defense-in-depth strategies such as validating input data types and structures at multiple layers of the stack rather than relying solely on transport-level or framework-level signature verification. Monitoring for anomalous XML parsing patterns can also help detect attempts to exploit this wrapping technique in real-time. Regular audits of cryptographic implementation practices are essential to prevent similar logical flaws from compromising system integrity in distributed environments.