OX Dovecot Pro CVE-2026-40016

Install the fixed version of OX Dovecot Pro as released by Open-Xchange GmbH per their security advisory. If an immediate patch is unavailable, implement the following compensating controls: disable or restrict access to the ManageSieve protocol (RFC 5804) via network firewall rules, limiting script management to out-of-band administrative processes; remove or restrict file system permissions for direct Sieve script placement in the local script directories; and reduce the configured Sieve CPU time limit to account for the 130x amplification factor until patched (e.g., if limit is 10 seconds, temporarily reduce to 0.08 seconds, with side effect of rejecting legitimately complex scripts). Monitor Sieve execution logs and server CPU utilization for signs of resource exhaustion attacks. These workarounds degrade user functionality and are temporary - prioritize patching as the primary remediation.