Vulnerability in Apache Cxf
CVE-2026-63687
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (20.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
- Apache Cxf
- Apache Software Foundation Cxf — versions 4.2.0, 4.0.0, 0
Weakness classification (CWE)
References
- lists.apache.org/thread/drcq4chmt0btx86f17o47j17r378hzpw (vendor-advisory, Mailing List, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2026-63687?
- CVE-2026-63687 is a critical-severity vulnerability in Apache Cxf, classified under Insufficient Verification of Data Authenticity. CVSS score: 9.1/10. Published 2026-08-06.
- How severe is CVE-2026-63687?
- Critical severity. CVSS v3 base score is 9.1 out of 10.