CVE-2021-22696: OAuth 2 authorization service vulnerable to DDos attacks
Apache CXF is vulnerable to a denial of service, caused by improper validation of requesturi parameter by the OAuth 2 authorization service. By sending a specially-crafted request, a remote attacker could exploit this vulnerability to cause a denial of service condition on the authorization server.
Other sources
CXF supports (via JwtRequestCodeFilter) passing OAuth 2 parameters via a JWT token as opposed to query parameters (see: The OAuth 2.0 Authorization Framework: JWT Secured Authorization Request (JAR)). Instead of sending a JWT token as a "request" parameter, the spec also supports specifying a URI from which to retrieve a JWT token from via the "requesturi" parameter. CXF was not validating the "requesturi" parameter (apart from ensuring it uses "https) and was making a REST request to the parameter in the request to retrieve a token. This means that CXF was vulnerable to DDos attacks on the authorization server, as specified in section 10.4.1 of the spec. This issue affects Apache CXF versions prior to 3.4.3; Apache CXF versions prior to 3.3.10.
Affected Software
Remediation
Patch Available
Patch Available
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the vulnerability ID for this Apache CXF vulnerability?
The vulnerability ID for this Apache CXF vulnerability is CVE-2021-22696.
What is the severity of CVE-2021-22696?
The severity of CVE-2021-22696 is high with a severity value of 7.5.
How does CVE-2021-22696 affect Apache CXF?
CVE-2021-22696 affects Apache CXF by causing a denial of service due to improper validation of the request_uri parameter.
Which versions of Apache CXF are affected by CVE-2021-22696?
Apache CXF versions up to and including 3.4.3 are affected by CVE-2021-22696.
How can I fix CVE-2021-22696?
To fix CVE-2021-22696, it is recommended to update Apache CXF to version 3.4.4 or higher.