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CVE-2026-40205

MEDIUMCVSS 5.9/10EPSS 0.18%

Last modified

CVE-2026-40205 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. EPSS estimates a 0.18% chance of exploitation in the next 30 days.

Description

An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. Use local token validation where tokens can be validated locally. Update to non-vulnerable version. No publicly available exploits are known.

Metrics

CVSS 3.1
5.9/10

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N

EPSS Probability
0.18%

7.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
Open-Xchange GmbHOX Dovecot Pro>= 2.3.11.2, < 2.3.22.2; >= 3.0.0, < 3.0.7; >= 3.1.0, < 3.1.6
Open-Xchange GmbHOX Dovecot CE>= 2.3.11.2, < 2.4.5

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-40205?
An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. Use local token validation where tokens can be validated locally. Update to non-vulnerable version. No publicly available exploits are known.
How severe is CVE-2026-40205?
CVE-2026-40205 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.
How do I fix CVE-2026-40205?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST