CVE-2026-27858

| EUVD-2026-16569 HIGH
2026-03-27 OX
7.5
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Patch Released
Mar 31, 2026 - 13:49 nvd
Patch available
EUVD ID Assigned
Mar 27, 2026 - 08:30 euvd
EUVD-2026-16569
Analysis Generated
Mar 27, 2026 - 08:30 vuln.today
CVE Published
Mar 27, 2026 - 08:10 nvd
HIGH 7.5

Tags

Denial Of Service Redhat

Description

Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.

Analysis

OX Dovecot Pro managesieve-login process crashes repeatedly due to memory exhaustion triggered by unauthenticated attackers sending crafted messages. The vulnerability enables remote denial of service against the managesieve protocol without authentication (CVSS:3.1/AV:N/AC:L/PR:N/UI:N), with a CVSS score of 7.5 (High severity). …

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Remediation

Within 24 hours: Inventory all Dovecot Pro deployments and confirm managesieve-login exposure to untrusted networks; document current versions and assess business criticality. Within 7 days: Implement network-level controls to restrict managesieve protocol access (port 4190) to trusted administrative networks only, or disable the managesieve-login service if not required for operations. …

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Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +38
POC: 0

Vendor Status

Ubuntu

Priority: Medium
dovecot
Release Status Version
trusty needed -
xenial needed -
bionic needed -
focal needed -
jammy needed -
noble needed -
questing needed -
upstream released 2.4.3

Debian

dovecot
Release Status Fixed Version Urgency
bullseye vulnerable 1:2.3.13+dfsg1-2+deb11u1 -
bullseye (security) vulnerable 1:2.3.13+dfsg1-2+deb11u2 -
bookworm, bookworm (security) vulnerable 1:2.3.19.1+dfsg1-2.1+deb12u1 -
trixie vulnerable 1:2.4.1+dfsg1-6+deb13u3 -
trixie (security) vulnerable 1:2.4.1+dfsg1-6+deb13u1 -
forky, sid vulnerable 1:2.4.2+dfsg1-4 -
(unstable) fixed (unfixed) -

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CVE-2026-27858 vulnerability details – vuln.today
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