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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (20.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 20.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
Weakness classification (CWE)
References
- documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2… (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.