Input validation error in Apache CXF - CVE-2026-63687
Published: August 24, 2026
Vulnerability identifier: #VU144830
CSH Severity: Low
CVSS v4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63687
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to undermine PKCE integrity and OpenID Connect replay protection.
The vulnerability exists due to improper input validation in JwtRequestCodeFilter when copying claims from a signed request JWT into the authorization parameter map. A remote user can provide a validly signed request JWT to override outer code_challenge, code_challenge_method, nonce, and state values to undermine PKCE integrity and OpenID Connect replay protection.
Exploitation requires the ability to produce a validly signed request JWT, such as when a client secret is known or compromised.
Affected software
Apache CXF
How to mitigate CVE-2026-63687
Install security update from vendor's website.
Apache CXF - addressed in versions 3.6.12, 4.1.8, 4.2.3