CVE-2026-40020: Open-Xchange OX Dovecot Pro · Improper Access Control
Affects Open-Xchange OX Dovecot ProSource CVE Database V5
Not known to be exploited · CVSS 3.1 Low.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:LExploitation evidence
Disclosed: evidence found.
CVE published 12 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Open-Xchange GmbHOX Dovecot Pro | Affected
| Fixed in– |
AI-suggested
The vendor advisory does not specify an official patch or remediation level. Users should monitor vendor communications for updates and apply any forthcoming patches promptly. Since the vulnerability requires the IMAP SETACL command and specific conditions, restricting access to IMAP services and reviewing ACL configurations may reduce exposure.
Description
Attacker can use the IMAP SETACL command to inject the anyone permission to user's dovecot-acl file even if imap_acl_allow_anyone=no. This causes folders to be spammed to all users. The impact is limited to being able to spam folders to other users, no unexpected access is gained. Install to fixed version. No publicly available exploits are known.