CVE-2026-27858: Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory

Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. No publicly available exploits are known.