High [CVE-2026-27858] denial of service via crafted message before authentication
This high-severity Red Hat Linux advisory covers CVE-2026-27858 affecting Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 7 Extended Lifecycle Support, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support.
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Summary
denial of service via crafted message before authentication. Red Hat rates this important (CVSS 7.5).
Weakness: CWE-770. Affected package(s): dovecot.
Resolved in Red Hat advisory RHSA-2026:26564 — update the affected packages (`sudo dnf update`).
Affected products named by the advisory: Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On; and 10 more.
- dovecot-1:2.2.36-8.el7_9.1
- dovecot-1:2.3.16-8.el9_2.2
- dovecot-1:2.3.16-3.el9_0.1
- dovecot-1:2.3.16-18.el9_8
- dovecot-1:2.3.21-19.el10_2
- dovecot-1:2.3.16-3.el8_8.1
- dovecot-1:2.3.8-9.el8_4.1
- dovecot-1:2.3.16-15.el9_6.1
- dovecot-1:2.3.21-16.el10_0.1
- dovecot-1:2.3.16-15.el9_7.1
- dovecot-1:2.3.16-11.el9_4.2
- dovecot-1:2.3.21-16.el10_1.1
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
- RHSA-2026:26564
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- Update the affected package(s) to the fixed version shipped in RHSA-2026:26564 (`sudo dnf update` / `yum update`).
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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