What’s Vulnerable › Vulnerabilities

CVE-2021-22696: OAuth 2 authorization service vulnerable to DDos attacks

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-02 · updated 2026-06-17
• Weakness: CWE-400

Description

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 "request_uri" parameter. CXF was not validating the "request_uri" 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 products

• Apache Software Foundation Apache CXF: before 3.3.10; from 3.4.0 before 3.4.3 — fixed in 3.3.10, 3.4.3
• Oracle Corporation Oracle Business Intelligence Enterprise Edition: 5.5.0.0.0, 5.9.0.0.0, 12.2.1.3.0, 12.2.1.4.0
• Oracle Communications Diameter Intelligence Hub: from 8.0.0 through 8.1.0; from 8.2.0 through 8.2.3
• Oracle Communications Element Manager: 8.2.2
• Oracle Communications Session Report Manager: from 8.0.0 through 8.2.4.0
• Oracle Communications Session Route Manager: from 8.0.0 through 8.2.4

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache CXF 3.3.10, 3.4.3. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2021/04/02/2
• https://cxf.apache.org/security-advisories.data/CVE-2021-22696.txt.asc
• https://lists.apache.org/thread.html/r6445001cc5f9a2bb1e6316993753306e054bdd1d702656b7cbe59045%40%3Cannounce.apache.org%3E
• https://lists.apache.org/thread.html/r8651c06212c56294a1c0ea61a5ad7790c06502209c03f05c0c7c9914%40%3Cdev.cxf.apache.org%3E
• https://lists.apache.org/thread.html/r8651c06212c56294a1c0ea61a5ad7790c06502209c03f05c0c7c9914%40%3Cusers.cxf.apache.org%3E
• https://lists.apache.org/thread.html/rec7160382badd3ef4ad017a22f64a266c7188b9ba71394f0d321e2d4%40%3Ccommits.cxf.apache.org%3E
• https://lists.apache.org/thread.html/rfb87e0bf3995e7d560afeed750fac9329ff5f1ad49da365129b7f89e%40%3Ccommits.cxf.apache.org%3E
• https://www.oracle.com/security-alerts/cpuapr2022.html
• https://www.oracle.com/security-alerts/cpuoct2021.html
• http://www.openwall.com/lists/oss-security/2021/04/02/2
• https://cxf.apache.org/security-advisories.data/CVE-2021-22696.txt.asc
• https://lists.apache.org/thread.html/r6445001cc5f9a2bb1e6316993753306e054bdd1d702656b7cbe59045%40%3Cannounce.apache.org%3E

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