What is CVE-2026-40020?

CVE-2026-40020 is a low-severity vulnerability in Dovecot, classified under Improper Access Control. CVSS score: 3.1/10. Published 2026-05-12.

How severe is CVE-2026-40020?

Low severity. CVSS v3 base score is 3.1 out of 10.

Vulnerability in Dovecot

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. 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.

EPSS: 0.003 (17.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L.

Affected products

Dovecot
Open-xchange Dovecot
Open-xchange Gmbh Ox Dovecot Pro — versions 0

Weakness classification (CWE)

CWE-284 — Improper Access Control

References

security@open-xchange.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-40020?: CVE-2026-40020 is a low-severity vulnerability in Dovecot, classified under Improper Access Control. CVSS score: 3.1/10. Published 2026-05-12.
How severe is CVE-2026-40020?: Low severity. CVSS v3 base score is 3.1 out of 10.