4.3

CVE-2026-40020: dovecot Improper Access Control

CVSS: 4.3v3.1MediumAnalyzed
AliasesALPINE-CVE-2026-40020UBUNTU-CVE-2026-40020DEBIAN-CVE-2026-40020
Published 12-05-2026Last modified 12-05-2026
Open JSON

Vulnerability summary

CVE-2026-40020 is a medium (CVSS 4.3) Improper Access Control vulnerability in dovecot. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 20.3% of scored vulnerabilities.

Overall risk
17/100
0100
Low · default modelHow is this calculated?
CVSS score
4.3/10
010
Medium · v3.1 (NVD)
EPSS score
0.29%
0%100%
Low · +0.03 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 6
OPENSUSE-SU-2026:10766-1OPENSUSE-SU-2026:21109-1SUSE-SU-2026:22185-1SUSE-SU-2026:2645-1SUSE-SU-2026:4139-1USN-8365-1

Timeline

  1. 12-05-2026
    PublishedVulnerability first disclosed.
  2. 12-05-2026
    Last modifiedVulnerability information updated.

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 metrics

5 scores · 5 sources · 1 version

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

20%

Versus all other CVEs

30-day change

+0.03 pp

From 0.26% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.29%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Alpine1 product
  • dovecot< 2.4.4-r0
Debian1 product
  • dovecot< 1:2.3.19.1+dfsg1-2.1+deb12u6 | < 1:2.4.1+dfsg1-6+deb13u6 | < 1:2.4.4+dfsg1-1
Dovecot1 product
Open-xchange1 product
Open-xchange gmbh1 product
Ubuntu1 product
  • dovecotAll versions (No fix recorded) | < 1:2.3.16+dfsg1-3ubuntu2.9 | < 1:2.3.21+dfsg1-2ubuntu6.5 | < 1:2.4.1+dfsg1-5ubuntu4.2 | < 1:2.4.2+dfsg1-3ubuntu2.1

6 vendors · 6 products

References

7 links