Auth bypass in Open-Xchange Gmbh Ox Dovecot Ce
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.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N.
EPSS exploit prediction
EPSS: 0.002 (10.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 10th percentile — 10.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-40205?
- CVE-2026-40205 is a medium-severity vulnerability in Open-Xchange Gmbh Ox Dovecot Ce, classified under Improper Authentication. CVSS score: 5.9/10. Published 2026-08-28.
- How severe is CVE-2026-40205?
- Medium severity. CVSS v3 base score is 5.9 out of 10.