Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-42395
Medium 4.3
In plain English
A medium-severity uncontrolled resource consumption 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 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A host listed as a trusted proxy can send forwarding information containing a NUL byte, which crashes the login process on the following login attempt. The login process is terminated, which can cause degradation or denial of service for logins. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-42395 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-42395 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-42395 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-42395 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-42395 |
| Ubuntu:22.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42395 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42395 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-42395 |
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-400 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L