CVE-2026-40020

Name: CVE-2026-40020
Creator: NVD / NIST
Published: 2026-05-12T14:17:03.687+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4.3/10EPSS 0.27%

Last modified Jun 17, 2026

CVE-2026-40020 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. 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. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

4.3/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

0.27%

18.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-284

Affected Software

Vendor	Product	Versions
Dovecot	Dovecot	< 2.4.4
Open-Xchange	Dovecot	< 3.1.5

References

https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.jsonVendor Advisory

Timeline

Published: May 12, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-40020?

How severe is CVE-2026-40020?

CVE-2026-40020 has a CVSS score of 4.3/10 (MEDIUM severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.

How do I fix CVE-2026-40020?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-40020?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST