Critical severity · published Aug 6, 2026
CVE-2026-63687
Apache CXF: JwtRequestCodeFilter silently overrides outer PKCE and nonce parameters
9.1
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AC
Apache CXF · Apache Software Foundation
4.2.0 before 4.2.3; 4.0.0 before 4.1.8; before 3.6.12 · source: vendor
CX
Cxf · Apache
before 3.6.12; 4.0.0 before 4.1.8; 4.2.0 before 4.2.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-63687
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-63687
Mailing List
https://lists.apache.org/thread/drcq4chmt0btx86f17o47j17r378hzpw
www.openwall.com
http://www.openwall.com/lists/oss-security/2026/08/06/22
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