CVE-2026-50630: Apache CXF: OAuth2: HTTP Response Splitting via WWW-Authenticate Realm Injection
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 or 3.6.12, which fixes this issue.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Apache CXF (OAuth2 / AuthorizationUtils)to a version that resolves this vulnerability.Fixed in 4.2.2 - Upgrade
Upgrade
Apache CXF (OAuth2 / AuthorizationUtils)to a version that resolves this vulnerability.Fixed in 4.1.7 - Upgrade
Upgrade
Apache CXF (OAuth2 / AuthorizationUtils)to a version that resolves this vulnerability.Fixed in 3.6.12 - Compensating control
If upgrading is not immediately possible, prevent attackers from controlling the OAuth2 realm value that is used to construct the 'WWW-Authenticate' header (because CR and LF are concatenated without sanitization, enabling HTTP header injection/response splitting for CVE-2026-50630).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-50630?
The severity of CVE-2026-50630 is rated as medium with a score of 6.5 according to the CVSS 3.1.
How do I fix CVE-2026-50630?
To fix CVE-2026-50630, sanitize any user-controlled input before concatenating it into the WWW-Authenticate response header.
What systems are affected by CVE-2026-50630?
CVE-2026-50630 affects Apache CXF, particularly versions that utilize the OAuth2 AuthorizationUtils class.
What type of vulnerability is CVE-2026-50630?
CVE-2026-50630 is categorized as a CRLF injection vulnerability.
What can an attacker achieve with CVE-2026-50630?
An attacker exploiting CVE-2026-50630 can inject malicious content into the HTTP response header by manipulating the 'realm' parameter.