CVE-2026-50630: Apache CXF: OAuth2: HTTP Response Splitting via WWW-Authenticate Realm Injection

[Colm O hEigeartaigh <coheigea () apache org>]

Severity: low 

Affected versions:

- Apache CXF (org.apache.cxf:cxf-rt-rs-security-oauth2) 4.2.0 before 4.2.2
- Apache CXF (org.apache.cxf:cxf-rt-rs-security-oauth2) before 4.1.7

Description:

A CRLF injection vulnerability exists in the OAuth2 AuthorizationUtils class. When constructing the WWW-Authenticate 
response header, the 'realm' parameter is concatenated without sanitizing Carriage Return (CR) and Line Feed (LF) 
characters. If an attacker can control the realm value, they can inject arbitrary HTTP headers or split the HTTP 
response entirely. Users are recommended to upgrade to versions 4.2.2 or 4.1.7, which fixes this issue.

Credit:

Guanping Zhang reported this vulnerability. (finder)

References:

https://cxf.apache.org/
https://www.cve.org/CVERecord?id=CVE-2026-50630