Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-42007
Critical 9.1
In plain English
A critical-severity use-after-free in OX Dovecot CE from Open-Xchange GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 28% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An attacker that has valid credentials can use a Sieve script with the editheader extension to trigger a use-after-free in the mail editing code, and to write memory contents beyond the intended buffer into the delivered mail. This causes memory leak and opportunity to do memory corruption during mail delivery, which can crash the delivery process and may allow execution of arbitrary code in the context of that process. Disable the Sieve editheader extension. Update to non-vulnerable version. No publicly available exploits are known.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | dovecot | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-devel | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-devel | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-devel | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-mysql | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-mysql | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-mysql | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-pgsql | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-pgsql | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-pgsql | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-pigeonhole | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-pigeonhole | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-pigeonhole | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| Alpine:v3.23 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-42007 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-42007 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-42007 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-42007 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-42007 |
| Rocky Linux:10 | dovecot | 1:2.3.21-19.el10_2.8 | RLSA-2026:79371 |
| Rocky Linux:8 | dovecot | 1:2.3.16-16.el8_10 | RLSA-2026:76763 |
| Rocky Linux:9 | dovecot | 1:2.3.16-18.el9_8.8 | RLSA-2026:80825 |
| Ubuntu:22.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42007 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42007 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42007 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro | 2.3.0 – before 2.3.22.23.0.0 – before 3.0.73.1.0 – before 3.1.6 |
| Open-Xchange GmbH | OX Dovecot CE | 2.3.0 – before 2.4.5 |
Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H