oss-security - [OSSA-2026-037] OpenStack Keystone: Inconsistent scope enforcement for delegated tokens (CVE-2026-pending)

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Message-ID: <7f909095-8110-4658-9c2e-6733f57da199@gmail.com>
Date: Tue, 25 Aug 2026 10:06:15 -0700
From: Goutham Pacha Ravi <gouthampravi@...il.com>
To: oss-security@...ts.openwall.com
Subject: [OSSA-2026-037] OpenStack Keystone: Inconsistent scope enforcement
 for delegated tokens (CVE-2026-pending)

==============================================================================
OSSA-2026-037: Inconsistent scope enforcement for delegated tokens in 
Keystone
==============================================================================

:Date: August 25, 2026
:CVE: CVE-2026-pending,
       CVE-2026-pending


Affects
~~~~~~~
- Keystone: >=13.0.0 <27.0.3, >=28.0.0 <28.0.3, >=29.0.0 <29.0.3


Description
~~~~~~~~~~~
Grzegorz Grasza (Red Hat) reported that OpenStack Keystone did not
consistently block delegated tokens from creating new long-lived
credentials or authorizing new delegations. Tim Shephard (roiai.ca)
separately reported that delegated tokens could be submitted to the
token-method authentication path to escape their project scope.

A token scoped through an OAuth1 access token, an application
credential, or a trust could create new long-lived credentials or
authorize new delegations that persist independently of, and outlive,
the credential used to obtain them. Separately, tokens obtained
through any of these delegation mechanisms could be submitted to the
token-method authentication path for reauthentication. When an
application credential token was presented with no explicit scope,
Keystone would issue a new token scoped to the credential owner's
default project rather than the project for which the credential was
issued, escaping the intended project boundary.

All Keystone deployments that permit delegated authentication through
OAuth1 access tokens, application credentials, or trusts are affected.


Patches
~~~~~~~
- https://review.opendev.org/1002307 (2025.1/epoxy)
- https://review.opendev.org/1002308 (2025.1/epoxy)
- https://review.opendev.org/1002305 (2025.2/flamingo)
- https://review.opendev.org/1002306 (2025.2/flamingo)
- https://review.opendev.org/1002303 (2026.1/gazpacho)
- https://review.opendev.org/1002304 (2026.1/gazpacho)
- https://review.opendev.org/1002301 (2026.2/hibiscus (development))
- https://review.opendev.org/1002302 (2026.2/hibiscus (development))


Credits
~~~~~~~
- Grzegorz Grasza from Red Hat
- Tim Shephard from roiai.ca


References
~~~~~~~~~~
- https://launchpad.net/bugs/2153453
- https://launchpad.net/bugs/2158538
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-pending
- http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-pending


Notes
~~~~~
- Two CVEs have been requested from MITRE for these vulnerabilities and
   are pending assignment.
- The two patch sets are interdependent and must be applied together.
   The token reauthentication guard introduced by the second patch
   depends on the delegation classification logic and the new ``[auth]
   additional_primary_auth_methods`` configuration option introduced by
   the first. Packaging or applying a subset is not supported.
- After upgrading, Keystone treats any authentication method not built
   in to Keystone as a delegated credential and rejects it from guarded
   operations (managing trusts, application credentials, and OAuth1
   access tokens, and token reauthentication). Deployments running a
   custom or third-party authentication plugin must add it to ``[auth]
   additional_primary_auth_methods`` or those authentication flows will
   fail.
- This advisory does not address a related weakness in EC2 credential
   (``ec2credential``) handling, which is being tracked and fixed in
   public and will be covered by a separate OpenStack Security Note
   (OSSN).
- A related fix to the Keystone Tempest plugin test suite was proposed
   at https://review.opendev.org/1002296

--
Goutham Pacha Ravi
OpenStack Vulnerability Management Team
https://security.openstack.org/vmt.html

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