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Fencer Vulns
medium 5.9

CVE-2026-40019 json

An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop…

published 2026-08-28 2 mo ago modified 2026-09-03 2 mo ago also EUVD-2026-67668

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • Open-Xchange GmbH OX Dovecot CE 2.4.5
  • dovecot Debian 14 1:2.4.5+dfsg1-1

debian advisories DEBIAN-CVE-2026-40019

  • dovecot RHEL 9 1:2.3.16-18.el9_8.8
  • dovecot-mysql RHEL 9 1:2.3.16-18.el9_8.8
  • dovecot-pgsql RHEL 9 1:2.3.16-18.el9_8.8
  • dovecot-pigeonhole RHEL 9 1:2.3.16-18.el9_8.8
  • dovecot RHEL 10.2 1:2.3.21-19.el10_2.8
  • dovecot-mysql RHEL 10.2 1:2.3.21-19.el10_2.8
  • dovecot-pgsql RHEL 10.2 1:2.3.21-19.el10_2.8
  • dovecot-pigeonhole RHEL 10.2 1:2.3.21-19.el10_2.8

red hat advisories RHSA-2026:80825RHSA-2026:79371RHSA-2026:76763

  • dovecot23 SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.3.21.1-150200.76.1
  • dovecot22 SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.2.31-19.40.1

suse advisories SUSE-SU-2026:4139-1SUSE-SU-2026:3919-1

  • dovecot24 openSUSE Tumbleweed 2.4.5-1.1

opensuse advisories openSUSE-SU-2026:11629-1

  • dovecot AlmaLinux 9 1:2.3.16-18.el9_8.8
  • dovecot-mysql AlmaLinux 9 1:2.3.16-18.el9_8.8
  • dovecot-pgsql AlmaLinux 9 1:2.3.16-18.el9_8.8
  • dovecot-pigeonhole AlmaLinux 9 1:2.3.16-18.el9_8.8
  • dovecot AlmaLinux 10 1:2.3.21-19.el10_2.8
  • dovecot-mysql AlmaLinux 10 1:2.3.21-19.el10_2.8
  • dovecot-pgsql AlmaLinux 10 1:2.3.21-19.el10_2.8
  • dovecot-pigeonhole AlmaLinux 10 1:2.3.21-19.el10_2.8

almalinux advisories ALSA-2026:80825ALSA-2026:79371ALSA-2026:76763

  • dovecot Rocky Linux 9 1:2.3.16-18.el9_8.8
  • dovecot Rocky Linux 10 1:2.3.21-19.el10_2.8
  • dovecot Rocky Linux 8 1:2.3.16-16.el8_10

rocky linux advisories RLSA-2026:80825RLSA-2026:79371RLSA-2026:76763

  • dovecot Alpine 3.24, Alpine 3.23 2.4.5-r0

alpine advisories ALPINE-CVE-2026-40019

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-40019 updated cvss 7.5

dovecot: Dovecot: Denial of Service via truncated quoted argument in ManageSieve

  • Red Hat Enterprise Linux 6 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 dovecot, dovecot-mysql, dovecot-pgsql, dovecot-pigeonhole
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) dovecot 2.3.16-16.el8_10, dovecot-mysql 2.3.16-16.el8_10, dovecot-pgsql 2.3.16-16.el8_10, dovecot-pigeonhole 2.3.16-16.el8_10
    fixed: vendor fix RHSA-2026:76763
  • Red Hat Enterprise Linux AppStream (v. 9) dovecot 2.3.16-18.el9_8.8, dovecot-mysql 2.3.16-18.el9_8.8, dovecot-pgsql 2.3.16-18.el9_8.8, dovecot-pigeonhole 2.3.16-18.el9_8.8
    fixed: vendor fix RHSA-2026:80825
  • Red Hat Enterprise Linux AppStream (v. 10) dovecot 2.3.21-19.el10_2.8, dovecot-mysql 2.3.21-19.el10_2.8, dovecot-pgsql 2.3.21-19.el10_2.8, dovecot-pigeonhole 2.3.21-19.el10_2.8
    fixed: vendor fix RHSA-2026:79371
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) dovecot 2.3.16-18.el9_8.8
    fixed: vendor fix RHSA-2026:80825
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) dovecot-devel 2.3.21-19.el10_2.8, dovecot-debuginfo 2.3.21-19.el10_2.8, dovecot-debugsource 2.3.21-19.el10_2.8, dovecot-mysql-debuginfo 2.3.21-19.el10_2.8, dovecot-pgsql-debuginfo 2.3.21-19.el10_2.8, dovecot-pigeonhole-debuginfo 2.3.21-19.el10_2.8
    fixed: vendor fix RHSA-2026:79371
  • Red Hat Enterprise Linux CRB (v. 8) dovecot 2.3.16-16.el8_10
    fixed: vendor fix RHSA-2026:76763

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Open-Xchange GmbH OX Dovecot CE

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.