CVE-2026-57817 Apache Software Foundation CVE debrief

Who should care

Administrators and developers using Apache CXF for OpenID Connect Hybrid Flow, especially those integrating with potentially non-compliant or misconfigured Identity Providers, should verify and validate `c_hash` parameter in Hybrid Flow. They should review and update configurations for compliance with OpenID Connect Core 1.0 specification and plan vendor-supported updates or mitigations through normal change control where exposure is confirmed. Additional focus should be on compensating controls for exposed systems while remediation is scheduled and verified. Relevant monitoring, detection, and logs for exposed assets that need extra review should be checked. Exceptions, retest remediated assets, and close the item only after evidence is documented should be tracked. This involves confirming whether affected product deployments exist in managed environments and assigning an owner for follow-up. Review of the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance is recommended. This affects operator, platform, vulnerability-management, and security-team impact, requiring a thorough review of configurations and potential exposure to authorization code substitution/injection attacks. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue. The OpenID Connect Core 1.0 specification requires validation of the `c_hash` parameter in Hybrid Flow. If an Apache CXF RP is integrated with a non-compliant or misconfigured Identity Provider (IdP) that omits the `c_hash`, the RP becomes vulnerable to Authorization Code Substitution/Injection attacks. Users are recommended to verify and validate `c_hash` parameter in Hybrid Flow with Identity Providers. The CVE record was published on 2026-08-06T11:16:30.120Z and has not been modified since then. Additional review of configurations for compliance with OpenID Connect Core 1.0 specification is necessary. Review compensating controls for exposed systems while remediation is scheduled and verified. Check relevant monitoring, detection, and logs for exposed assets that need extra review. Track exceptions, retest remediated assets, and close the item. A

Technical summary

The OpenID Connect Core 1.0 specification mandates validation of the `c_hash` parameter in Hybrid Flow. Apache CXF RP integrated with non-compliant or misconfigured IdP omitting `c_hash` is vulnerable to authorization code substitution/injection attacks. Fixed in versions 4.2.3, 4.1.8, and 3.6.12. Users should review and update configurations for compliance with OpenID Connect Core 1.0 specification. Administrators and developers using Apache CXF for OpenID Connect Hybrid Flow should especially focus on integrating with potentially non-compliant or misconfigured Identity Providers.

Defensive priority

High priority due to potential for authorization code substitution/injection attacks

Recommended defensive actions

• Upgrade to Apache CXF version 4.2.3, 4.1.8, or 3.6.12
• Verify and validate `c_hash` parameter in Hybrid Flow with Identity Providers
• Review and update configurations for compliance with OpenID Connect Core 1.0 specification
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

Evidence from NVD and Apache security advisories indicates a vulnerability in Apache CXF's OpenID Connect implementation. Limited details are available on exploitability and affected systems. The OpenID Connect Core 1.0 specification mandates that the RP MUST validate the `c_hash` parameter when operating in the Hybrid Flow. Users are recommended to verify and validate `c_hash` parameter in Hybrid Flow with Identity Providers. The CVE record was published on 2026-08-06T11:16:30.120Z and has not been modified since then. Additional review of configurations for compliance with OpenID Connect Core 1.0 specification is necessary.

Official resources