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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache CXF | 4.2.0 – < 4.2.3, 4.0.0 – < 4.1.8, < 3.6.12 | 4.2.3 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | ovirt-engine-wildfly +1 | 24.0.1-4.el9 | ELSA-2026-500571 |
| Oracle Linux 8 | ovirt-engine-wildfly +1 | 24.0.1-4.el8 | ELSA-2026-500570 |
Advisories 3
- WID-SEC-2026-2682 Apache CXF: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ELSA-2026-500571 Important: ovirt-engine-wildfly security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Nov 4, 2026
- ELSA-2026-500570 Important: ovirt-engine-wildfly security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Nov 4, 2026
References
- https://lists.apache.org/thread/pj63c3pf7kkp1xhr53do704fwj3t3htn vendor-advisory