CVE-2026-61466: Apache CXF: OAuth2 Dynamic Client Registration Scope Self-Escalation

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-06 · updated 2026-10-24
Weakness: CWE-304

Description

In Apache CXF's OAuth2 Dynamic Client Registration endpoint, the authorization server accepts and stores the `scope` value supplied in the client registration request verbatim, without validating it against an AS-defined allowlist. This could lead to a client self-assigning privileged scopes at registration time. Users are recommended to upgrade to versions 4.2.3 or 4.1.8 or 3.6.12, which fix this issue.

Affected products

Apache Software Foundation Apache CXF: before 3.6.12; from 4.0.0 before 4.1.8; from 4.2.0 before 4.2.3 — fixed in 3.6.12, 4.1.8, 4.2.3

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache CXF 3.6.12, 4.1.8, 4.2.3. Check the vendor advisory for mitigations.

References

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