CVE-2026-61466
Description
A flaw was found in Apache CXF. The OAuth2 Dynamic Client Registration endpoint in Apache CXF does not properly validate the scope value provided during client registration. This oversight allows a malicious client to assign itself privileged access scopes, potentially leading to unauthorized access or privilege escalation within the system.
Statement
This flaw has a Moderate impact on Red Hat products that ship the Apache CXF OAuth2 module (cxf-rt-rs-security-oauth2). In CXF's OAuth2 Dynamic Client Registration endpoint, the authorization server stores the scope value supplied in a client registration request without validating it against a server-defined allowlist, so a client can self-assign privileged scopes at registration time and gain unauthorized access to protected resources. Exploitation requires that the Dynamic Client Registration endpoint be deployed and reachable. Red Hat products that bundle Apache CXF only for SOAP/JAX-WS web services do not ship the OAuth2 module and are not affected.
Mitigation
Restrict or disable the OAuth2 Dynamic Client Registration endpoint, or place it behind an authenticated administrative interface, so that untrusted clients cannot self-register with attacker-chosen scopes. Where the endpoint must remain enabled, enforce server-side validation of requested scopes against an allowlist.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.4 | N/A | 9.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | High |
| Integrity Impact | Low | N/A | None |
| Availability Impact | None | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Understanding the Weakness (CWE)
Access Control
Technical Impact: Gain Privileges or Assume Identity
A user can access restricted functionality and/or sensitive information that may include administrative functionality and user accounts.
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