Medium severity · published May 12, 2026
CVE-2026-40020
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
4.3
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 18% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OD
OX Dovecot Pro · Open-Xchange GmbH
through 2.3.0 · source: vendor
DO
Dovecot · Dovecot
before 2.4.4 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40020
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-40020
Vendor Advisory
https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.json
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