Quick answers
- Is CVE-2026-40205 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-40205 being exploited in the wild.
- How severe is CVE-2026-40205?
- Medium severity, with a CVSS score of 5.9, published 28 August 2026.
- Which products and versions are affected?
- Open-Xchange Dovecot Pro 2.3.0 to 2.3.22.1, 3.0.0 to 3.0.6, 3.1.0 to 3.1.5.
- Is there a fix for CVE-2026-40205?
- A patch was published on 2026-08-28: Patched versions 2.3.22.2, 3.0.7, 3.1.6 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-40205 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-40205?
- Check whether you run Open-Xchange Dovecot Pro at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is an authorization bypass in OAuth2 scope validation. When multiple scopes are required in the authorization configuration, the remote token validation path incorrectly accepts tokens carrying only one of the required scopes, while the local token validation path correctly enforces all scopes. This inconsistency allows an attacker with a partially-privileged OAuth2 token to authenticate successfully where they should be rejected. The attack requires possession of a valid OAuth2 token with reduced scope grants; no user interaction or local access is needed. The fix is to use local token validation exclusively or update to patched versions 2.3.22.2, 3.0.7, or 3.1.6.
Affected products
- Open-Xchange Dovecot Pro 2.3.0 to 2.3.22.1, 3.0.0 to 3.0.6, 3.1.0 to 3.1.5
Timeline
- 2026-08-28: disclosed
- 2026-08-26: advisory: OXDC-ADV-2026-0003 initial release
- 2026-08-28: patched: Patched versions 2.3.22.2, 3.0.7, 3.1.6 released