CVE-2026-52681

A flaw was found in dovecot. An authenticated attacker can bypass the configured Sieve CPU limit by repeatedly changing active scripts. This action prevents proper CPU resource accounting and leaves behind compiled script files, leading to sustained CPU and increased disk consumption. The consequence is a degradation of service for mail delivery, potentially causing a Denial of Service (DoS).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Administrators can monitor system resources for abnormal CPU usage and disk consumption related to Dovecot Sieve processes. To prevent exploitation, if Sieve functionality is not required, it can be disabled by removing the sieve plugin from the mail_plugins setting in the Dovecot configuration. Disabling Sieve will impact user mail filtering capabilities. A restart of the Dovecot service is required for configuration changes to take effect.