OpenStack Keystone RBAC Bypass via Untrusted JSON Merge (pre-29.0.2)
CVE-2026-42999 Published on May 28, 2026
An issue was discovered in OpenStack Keystone before 29.0.2. The Keystone RBAC policy enforcer in enforce_call unconditionally merges the raw JSON request body into the policy enforcement dictionary via policy_dict.update(json_input.copy()), overwriting trusted target data that was previously set from database lookups. Because flask.request.get_json is called with force=True, this works regardless of Content-Type or HTTP method. Any authenticated user can inject arbitrary policy target attributes (e.g., user_id, project_id) into the request body to bypass RBAC checks and perform unauthorized operations on resources belonging to other users or projects. This was introduced in commit 5ea59f52 (Rocky/14.0.0).
Vulnerability Analysis
CVE-2026-42999 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality and integrity, and a small impact on availability.
Weakness Types
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2026-42999 has been classified to as an AuthZ vulnerability or weakness.
What is an Insecure Direct Object Reference / IDOR Vulnerability?
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
CVE-2026-42999 has been classified to as an Insecure Direct Object Reference / IDOR vulnerability or weakness.
Products Associated with CVE-2026-42999
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Affected Versions
OpenStack Keystone:- Version 14.0.0 and below 27.0.2 is affected.
- Version 28.0.0 and below 28.0.2 is affected.
- Version 29.0.0 and below 29.0.2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.