Description
An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known.
Published: 2026-08-28
Score: 7.4 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

Fri, 28 Aug 2026 14:30:00 +0000

Type Values Removed Values Added
Title OAuth2 Token Misuse Enables Unauthorized Authentication

Fri, 28 Aug 2026 11:30:00 +0000

Type Values Removed Values Added
Description An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known.
Weaknesses CWE-287
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}


Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published:

Updated: 2026-08-28T15:53:21.257Z

Reserved: 2026-08-11T13:14:10.017Z

Link: CVE-2026-73208

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-28T12:16:31.127

Modified: 2026-08-28T20:19:45.063

Link: CVE-2026-73208

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-28T14:15:04Z

Weaknesses