CVE-2026-42006: dovecot Uncontrolled Resource Consumption

Vulnerability summary

CVE-2026-42006 is a medium (CVSS 4.3) Uncontrolled Resource Consumption vulnerability in dovecot. EPSS estimates a 0.82% chance of exploitation in the next 30 days, higher than 56.6% of scored vulnerabilities.

Timeline

1. 12-05-2026
   PublishedVulnerability first disclosed.
2. 03-08-2026
   Last modifiedVulnerability information updated.

Description

An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.

• CWE-400Uncontrolled Resource ConsumptionThe product does not properly control the allocation and maintenance of a limited resource.
• CWE-770Allocation of Resources Without Limits or ThrottlingThe product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.