A local privilege escalation vulnerability in the zmmailboxdmgr launcher of Zimbra Collaboration Suite (ZCS) allows the Unix zimbra account to… (CVE-2026-50056)

CVE-2026-50056 is a local privilege escalation vulnerability in the zmmailboxdmgr launcher component of Zimbra Collaboration Suite (ZCS). The vulnerability arises because the passwordless sudo interface accepts JVM arguments without adequate restrictions. An attacker with local command execution as the Unix zimbra user on a mailbox server can postpone Jetty's privilege drop and register an OnOutOfMemoryError command. By forcing heap exhaustion during startup, the attacker causes the JVM to execute the registered command while still running as root, thereby escalating privileges from zimbra to root. The affected versions explicitly stated are ZCS 10.1.16 and 10.1.21.

Successful exploitation allows an attacker with local access as the zimbra user to execute arbitrary commands with root privileges on the mailbox server. This leads to full system compromise, including confidentiality, integrity, and availability impacts as indicated by the CVSS vector (C:H/I:H/A:H).

No patch or official fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict local access to the zimbra user and avoid interrupting mailboxd during restarts. Monitor vendor communications for updates on remediation.