Resource exhaustion in Dovecot and OX Dovecot Pro - CVE-2026-27859
Published: April 1, 2026
Vulnerability identifier: #VU124727
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:U/U:Green
CVE-ID: CVE-2026-27859
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Dovecot
Affected software:
Dovecot
OX Dovecot Pro
Dovecot
OX Dovecot Pro
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to uncontrolled resource consumption in MIME parameter parsing when processing message headers. A remote attacker can send a specially crafted email message with excessive RFC 2231 MIME parameters to cause a denial of service of the LMTP mail delivery process.
How to mitigate CVE-2026-27859
Install security update from vendor's website.