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OpenAdvisories
Medium · 4.3 CVE-2026-40013 EUVD-2026-67663GHSA-jh33-8ccj-9h78

An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal, which causes an out-of-bounds write…

Published Aug 28, 2026 · Updated Aug 28, 2026 · Assigned by OX

Description

An attacker that has valid credentials can submit a Sieve script containing an extreme numeric literal, which causes an out-of-bounds write when the ManageSieve service compiles the script. This causes memory corruption and an observed crash of the ManageSieve process, resulting in denial of service for script management. This might be able to be used for remote code execution. Disable the ManageSieve service if users do not need remote Sieve script management. Update to non-vulnerable version. No publicly available exploits are known.

Affected products

VendorProductAffectedFixed
Open-Xchange OX Dovecot Pro 2.3.0 – < 2.3.22.2, 3.0.0 – < 3.0.7, 3.1.0 – < 3.1.6 2.3.22.2
Open-Xchange OX Dovecot CE 2.3.0 – < 2.4.5 2.4.5

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 dovecot 1:2.4.5+dfsg1-1 —
Debian 13 dovecot 1:2.4.1+dfsg1-6+deb13u7 —
Debian 12 dovecot 1:2.3.19.1+dfsg1-2.1+deb12u7 —
ReleasePackageFixed inAdvisory
Ubuntu 26.04 LTS dovecot No fix yet —
Ubuntu 24.04 LTS dovecot No fix yet —
Ubuntu 22.04 LTS dovecot No fix yet —
Ubuntu 20.04 LTS dovecot No fix yet —
Ubuntu 18.04 LTS dovecot No fix yet —
Show 2 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu 16.04 LTS dovecot No fix yet —
Ubuntu Pro 14.04 LTS dovecot No fix yet —
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 dovecot24 2.4.4-160000.2.1 SUSE-SU-2026:23595-1
SLES 16.0 dovecot24 2.4.4-160000.2.1 SUSE-SU-2026:23595-1
ReleasePackageFixed inAdvisory
openSUSE Leap 16.0 dovecot24 2.4.4-160000.2.1 openSUSE-SU-2026:21720-1

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 dovecot No fix yet —

Advisories 3

References