Apache CXF RP c_hash Validation Flaw fixed in 4.2.3, 4.1.8, 3.6.12
CVE-2026-57817 Published on August 6, 2026
Apache CXF: The authorization code hash (c_hash) is not enforced for the hybrid OIDC flow
The OpenID Connect Core 1.0 specification mandates that the RP MUST validate the `c_hash` parameter when operating in the 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 upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.
Vulnerability Analysis
CVE-2026-57817 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Products Associated with CVE-2026-57817
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Affected Versions
Apache Software Foundation Apache CXF:- Version 4.2.0 and below 4.2.3 is affected.
- Version 4.0.0 and below 4.1.8 is affected.
- Before 3.6.12 is affected.