VulnerabilityModified

CVE-2026-57817

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.

HIGH 8.1EPSS 0.45%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

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.

CVSS 3.1: 8.1 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.45% probability · 38th percentile
CISA KEV: Not listed
Weakness: CWE-20
Affected: apache/cxf
Source: security@apache.org

References

https://lists.apache.org/thread/pj63c3pf7kkp1xhr53do704fwj3t3htnMailing List, Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/08/06/19

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.