CVE-2026-40019

dovecot: An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spi...

CVE-2026-40019 is fixed in 11 products on 1 platform, first by RHSA-2026:79371, released August 28, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
9.1
important
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0037
31st percentile

An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve script management, and repeated connections can consume all available CPU on the server. Monitor system for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.

Where it's fixed

ProductFixed inFixReleased
Linux
dovecot · Debian 14 1:2.4.5+dfsg1-1 DEBIAN-CVE-2026-40019 Sep 10, 2026
dovecot · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot · RHEL 10 2.3.21-19.el10_2.8 RHSA-2026:79371 Aug 28, 2026
dovecot · RHEL 8 1:2.3.16-16.el8_10 RHSA-2026:76763 Oct 6, 2026
dovecot · RHEL 9 1:2.3.16-18.el9_8.8 RHSA-2026:80825 Oct 13, 2026
dovecot · almalinux 10 1:2.3.21-19.el10_2.8 ALSA-2026:79371 Oct 8, 2026
dovecot · almalinux 8 1:2.3.16-16.el8_10 ALSA-2026:76763 Oct 6, 2026
dovecot · almalinux 9 1:2.3.16-18.el9_8.8 ALSA-2026:80825 Nov 7, 2026
dovecot · ol 10 1:2.3.21-19.el10_2.8 ELSA-2026-79371 Oct 8, 2026
dovecot · ol 8 1:2.3.16-16.el8_10 ELSA-2026-76763 Oct 6, 2026
dovecot · ol 9 1:2.3.16-18.el9_8.8 ELSA-2026-80825 Nov 7, 2026
dovecot · rocky 10 1:2.3.21-19.el10_2.8 RLSA-2026:79371 Nov 7, 2026
dovecot · rocky 8 1:2.3.16-16.el8_10 RLSA-2026:76763 Oct 7, 2026
dovecot · rocky 9 1:2.3.16-18.el9_8.8 RLSA-2026:80825 Nov 7, 2026
dovecot-debuginfo · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-debugsource · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-devel · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-devel · RHEL 8 1:2.3.16-16.el8_10 RHSA-2026:76763 Oct 6, 2026
dovecot-devel · RHEL 9 1:2.3.16-18.el9_8.8 RHSA-2026:80825 Oct 13, 2026
dovecot-devel · almalinux 10 1:2.3.21-19.el10_2.8 ALSA-2026:79371 Oct 8, 2026
dovecot-devel · almalinux 8 1:2.3.16-16.el8_10 ALSA-2026:76763 Oct 6, 2026
dovecot-devel · almalinux 9 1:2.3.16-18.el9_8.8 ALSA-2026:80825 Nov 7, 2026
dovecot-devel · ol 10 1:2.3.21-19.el10_2.8 ELSA-2026-79371 Oct 8, 2026
dovecot-devel · ol 8 1:2.3.16-16.el8_10 ELSA-2026-76763 Oct 6, 2026
dovecot-devel · ol 9 1:2.3.16-18.el9_8.8 ELSA-2026-80825 Nov 7, 2026
dovecot-mysql · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-mysql · RHEL 8 1:2.3.16-16.el8_10 RHSA-2026:76763 Oct 6, 2026
dovecot-mysql · RHEL 9 1:2.3.16-18.el9_8.8 RHSA-2026:80825 Oct 13, 2026
dovecot-mysql · almalinux 10 1:2.3.21-19.el10_2.8 ALSA-2026:79371 Oct 8, 2026
dovecot-mysql · almalinux 8 1:2.3.16-16.el8_10 ALSA-2026:76763 Oct 6, 2026
dovecot-mysql · almalinux 9 1:2.3.16-18.el9_8.8 ALSA-2026:80825 Nov 7, 2026
dovecot-mysql · ol 10 1:2.3.21-19.el10_2.8 ELSA-2026-79371 Oct 8, 2026
dovecot-mysql · ol 8 1:2.3.16-16.el8_10 ELSA-2026-76763 Oct 6, 2026
dovecot-mysql · ol 9 1:2.3.16-18.el9_8.8 ELSA-2026-80825 Nov 7, 2026
dovecot-mysql-debuginfo · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-pgsql · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-pgsql · RHEL 8 1:2.3.16-16.el8_10 RHSA-2026:76763 Oct 6, 2026
dovecot-pgsql · RHEL 9 1:2.3.16-18.el9_8.8 RHSA-2026:80825 Oct 13, 2026
dovecot-pgsql · almalinux 10 1:2.3.21-19.el10_2.8 ALSA-2026:79371 Oct 8, 2026
dovecot-pgsql · almalinux 8 1:2.3.16-16.el8_10 ALSA-2026:76763 Oct 6, 2026
dovecot-pgsql · almalinux 9 1:2.3.16-18.el9_8.8 ALSA-2026:80825 Nov 7, 2026
dovecot-pgsql · ol 10 1:2.3.21-19.el10_2.8 ELSA-2026-79371 Oct 8, 2026
dovecot-pgsql · ol 8 1:2.3.16-16.el8_10 ELSA-2026-76763 Oct 6, 2026
dovecot-pgsql · ol 9 1:2.3.16-18.el9_8.8 ELSA-2026-80825 Nov 7, 2026
dovecot-pgsql-debuginfo · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-pigeonhole · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot-pigeonhole · RHEL 8 1:2.3.16-16.el8_10 RHSA-2026:76763 Oct 6, 2026
dovecot-pigeonhole · RHEL 9 1:2.3.16-18.el9_8.8 RHSA-2026:80825 Oct 13, 2026
dovecot-pigeonhole · almalinux 10 1:2.3.21-19.el10_2.8 ALSA-2026:79371 Oct 8, 2026
dovecot-pigeonhole · almalinux 8 1:2.3.16-16.el8_10 ALSA-2026:76763 Oct 6, 2026
dovecot-pigeonhole · almalinux 9 1:2.3.16-18.el9_8.8 ALSA-2026:80825 Nov 7, 2026
dovecot-pigeonhole · ol 10 1:2.3.21-19.el10_2.8 ELSA-2026-79371 Oct 8, 2026
dovecot-pigeonhole · ol 8 1:2.3.16-16.el8_10 ELSA-2026-76763 Oct 6, 2026
dovecot-pigeonhole · ol 9 1:2.3.16-18.el9_8.8 ELSA-2026-80825 Nov 7, 2026
dovecot-pigeonhole-debuginfo · Fedora 43 1:2.4.5-1.fc43 FEDORA-2026-E8A6485109 Sep 10, 2026
dovecot23 · sles 15.6 2.3.21.1-150200.76.1 SUSE-SU-2026:4139-1 Sep 14, 2026
dovecot23 · sles 15.7 2.3.21.1-150200.76.1 SUSE-SU-2026:4139-1 Sep 14, 2026

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