What is CVE-2026-50056?

CVE-2026-50056 is a high-severity vulnerability in Zimbra Collaboration Suite, classified under Argument Injection. CVSS score: 7.8/10. Published 2026-10-23.

How severe is CVE-2026-50056?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in Zimbra Collaboration Suite

CVE-2026-50056

A local privilege escalation vulnerability in the zmmailboxdmgr launcher of Zimbra Collaboration Suite (ZCS) allows the Unix zimbra account to execute arbitrary commands as root. The passwordless sudo interface accepts JVM arguments that are not adequately restricted. An attacker can postpone Jetty's privilege drop, register an OnOutOfMemoryError command and force heap exhaustion during startup, causing the command to execute while the JVM still runs as root. Exploitation requires local command execution as zimbra on a mailbox server and interrupts mailboxd during the malicious restart. ZCS 10.1.16 and 10.1.21 are affected.

Published 2026-10-23 · last modified 2026-10-23.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Zimbra Collaboration Suite

Weakness classification (CWE)

CWE-88 — Argument Injection

References

wiki.zimbra.com/wiki/Zimbra_Security_Advisories (vendor-advisory)
www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/ (related)

Frequently asked questions

What is CVE-2026-50056?: CVE-2026-50056 is a high-severity vulnerability in Zimbra Collaboration Suite, classified under Argument Injection. CVSS score: 7.8/10. Published 2026-10-23.
How severe is CVE-2026-50056?: High severity. CVSS v3 base score is 7.8 out of 10.