RHSA-2026:19455 - Security Advisory

Topic

An update for dovecot is now available for Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

Dovecot is an IMAP server for Linux and other UNIX-like systems, written primarily with security in mind. It also contains a small POP3 server, and supports e-mail in either the maildir or mbox format. The SQL drivers and authentication plug-ins are provided as subpackages.

Security Fix(es):

• dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command (CVE-2025-59032)
• dovecot: denial of service via crafted message before authentication (CVE-2026-27858)
• dovecot: denial of service via specially crafted NOOP command (CVE-2026-27857)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support Extension 8.4 x86_64
• Red Hat Enterprise Linux Server - AUS 8.4 x86_64

Fixes

• BZ - 2452172 - CVE-2025-59032 dovecot: ManageSieve: Denial of Service via crafted SASL initial response in AUTHENTICATE command
• BZ - 2452175 - CVE-2026-27858 dovecot: denial of service via crafted message before authentication
• BZ - 2452179 - CVE-2026-27857 dovecot: denial of service via specially crafted NOOP command

CVEs

• CVE-2025-59032
• CVE-2026-27857
• CVE-2026-27858

References

• https://access.redhat.com/security/updates/classification/#important