PT-2026-28366 · Dovecot+3 · Dovecot+3

Ilyar · Published 2026-01-01 · Updated 2026-05-19 · CVE-2026-27858

Positive Technologies (AI Summary)

CVSS v3.1

7.5

High

Base vector

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

Name of the Vulnerable Software and Affected Versions Dovecot versions prior to 2.4.3

Description An attacker can send a crafted message before authentication, leading to excessive memory allocation within the managesieve component. This can cause the managesieve-login process to crash, potentially resulting in a denial-of-service condition. No publicly available exploits are currently known.

Recommendations Update to version 2.4.3 or later. Protect access to the managesieve protocol.

Fix

DoS

Resource Exhaustion

Weakness Enumeration

CWE-400

Related Identifiers

ALSA-2026:13498

ALSA-2026:13830

ALSA-2026:13857

ALSA-2026:19149

ALSA-2026:19364

CVE-2026-27858

OESA-2026-1849

OPENSUSE-SU-2026:10442-1

OPENSUSE-SU-2026:20554-1

RHSA-2026:13498

RHSA-2026:13830

RHSA-2026:13857

SUSE-SU-2026:21208-1

USN-8136-1

Affected Products

Dovecot

Linuxmint

Rocky Linux

Ubuntu

References · 80

• https://ubuntu.com/security/CVE-2026-27856 · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2026-13830.html · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27856 · Security Note
• https://osv.dev/vulnerability/ALSA-2026:13830 · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:13857 · Vendor Advisory
• https://osv.dev/vulnerability/ALSA-2026:19149 · Vendor Advisory
• https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-19364.html · Vendor Advisory
• https://errata.almalinux.org/9/ALSA-2026-13857.html · Vendor Advisory
• https://osv.dev/vulnerability/OESA-2026-1849 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-0394 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27858 · Security Note
• https://errata.almalinux.org/8/ALSA-2026-13830.html · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-27857 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:21208-1 · Vendor Advisory