# CVE-2026-50056: Zimbra Collaboration Suite Local Privilege Escalation via zmmailboxdmgr JVM Argument Injection


- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** GHSA-ww99-8662-82q8

## What is CVE-2026-50056?

CVE-2026-50056 is a high-severity vulnerability in Zimbra Collaboration Suite, published on 23 Oct 2026. 

### Official description

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.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command)

## Which versions are affected by CVE-2026-50056?


## How do I fix CVE-2026-50056?

No fix has been published for CVE-2026-50056 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-50056 being exploited?

There is no known exploitation of CVE-2026-50056 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50056 and fix it if it is affected.

What it is: CVE-2026-50056 is a high-severity vulnerability in Zimbra Collaboration Suite, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-50056 in the wild and no public exploit code.

Affected product: Zimbra Collaboration Suite. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-50056/ (Markdown: https://insights.sbomify.com/CVE-2026-50056/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50056
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50056
- OSV: https://osv.dev/vulnerability/CVE-2026-50056

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-50056/
Summaries are generated and may contain mistakes; the official description above is the record.