Apache CXF JWT Claim Copy JwtRequestCodeFilter disrupts PKCE (3.6.12/4.1.8/4.2.3)
CVE-2026-63687 Published on August 6, 2026
Apache CXF: JwtRequestCodeFilter silently overrides outer PKCE and nonce parameters
Apache CXF's JwtRequestCodeFilter copies all claims from a signed request JWT into the authorization parameter map without excluding security-sensitive parameters. A client that can produce a validly-signed request JWT (e.g., one whose client_secret is known or compromised) can thereby substitute the code_challenge, code_challenge_method, nonce, and state values that were set in the outer HTTP request, undermining PKCE integrity and OpenID Connect replay protection. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.
Vulnerability Analysis
CVE-2026-63687 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 have a high impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Insufficient Verification of Data Authenticity
The software does not sufficiently verify the origin or authenticity of data, in a way that causes it to accept invalid data.
Products Associated with CVE-2026-63687
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Affected Versions
Apache Software Foundation Apache CXF:- Version 4.2.0 and below 4.2.3 is affected.
- Version 4.0.0 and below 4.1.8 is affected.
- Before 3.6.12 is affected.