Improper access control in Dovecot and OX Dovecot Pro - CVE-2026-40020
Published: May 19, 2026
Vulnerability identifier: #VU131868
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-40020
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Dovecot
Affected software:
Dovecot
OX Dovecot Pro
Dovecot
OX Dovecot Pro
Detailed vulnerability description
The vulnerability allows a remote user to spam folders to other users.
The vulnerability exists due to improper access control in the IMAP SETACL command when injecting the anyone permission into a user's dovecot-acl file. A remote user can use the IMAP SETACL command to spam folders to other users.
No unexpected access is gained.
How to mitigate CVE-2026-40020
Install security update from vendor's website.