CVE-2026-59358 UAA OAuth Token Endpoint Vulnerability allows user access token reuse for client_credentials grant type
Authenticated users can bypass client authentication to obtain privileged client credentials, enabling privilege escalation and arbitrary client creation in Cloud Foundry UAA.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-59358?
CVE-2026-59358 is a high-severity authentication bypass vulnerability in Cloud Foundry UAA, published on 6 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Improper authentication (CWE-287) in the OAuth token endpoint in Cloud Foundry UAA allows a remote, authenticated attacker holding a valid user access token to obtain a fully-privileged client_credentials token for the OAuth client that issued it, by presenting the user token as an OAuth 2.0 Bearer credential on a client_credentials grant request in place of the client’s configured secret.
UAA’s client_credentials handling does not verify that the Bearer credential supplied for client authentication is actually a client credential (a client secret or a valid configured client authentication method); it accepts any valid access token whose client_id matches the request. A token obtained by a normal end user through a public authorization_code + PKCE flow — scoped only to uaa.user, carrying a user_id, and recording client_auth_method=none — satisfies this check. That user token cannot itself administer OAuth clients (POST /oauth/clients correctly returns 403), but when replayed as Bearer authentication on a client_credentials request for the same client, UAA issues a new client-only token carrying the client’s full authorities, such as clients.write. An attacker can use that token to create arbitrary new OAuth clients, including clients with attacker-chosen authorities, without ever possessing the client’s actual secret.
Exploitation requires a valid user access token (the attacker’s own) for a client that is configured to support both a public, user-facing authorization flow and the client_credentials grant type on the same client_id — a non-default combination. Practical impact scales with the authorities assigned to that client.
Weakness: CWE-287
Which versions are affected by CVE-2026-59358?
How do I fix CVE-2026-59358?
No fix has been published for CVE-2026-59358 yet. Limit exposure of the affected software until one is available.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-59358 being exploited?
There is no known exploitation of CVE-2026-59358 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-hqp7-g6vh-8mf8.