MEDIUM
CVE-2026-40020
CWE-284Published: May 12, 2026· Updated: May 18, 2026
4.3
CVSS v3.1
EPSS:0.01%probability of exploitation in 30 daysPercentile:1.5th
Official 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.
Technical Analysis
CVE-2026-40020 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Affected Vendors & Products
dovecot1 product
dovecot
open-xchange1 product
dovecot
Source: NVD CPE · 2 total CPE entries
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (1)
Quick Facts
CVE IDCVE-2026-40020
CVSS Score4.3 / 10
SeverityMEDIUM
WeaknessCWE-284
CISA KEVNo
EPSS (30d)0.01%
Affected2 vendors
PublishedMay 12, 2026
Related CVEs (CWE-284)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-40020 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.