Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-40015
Medium 4.3
In plain English
A medium-severity out-of-bounds read 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 0.6% (higher than 46% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An attacker that has valid credentials can open many connections to the imap-hibernate service and send invalid commands, which can intermittently cause an out-of-bounds read and crash the process. The crash interrupts hibernated IMAP sessions handled by the affected process, which can cause degradation of service for IMAP. Disable IMAP hibernation. 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-2026-40015 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-40015 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-40015 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-40015 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-40015 |
| Ubuntu:22.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40015 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40015 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40015 |
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-125 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L