# CVE-2018-20160: XML external entity in n/a

> Attackers can exploit XML External Entity vulnerabilities in Zimbra Chat to read sensitive data or execute code via crafted requests.

- **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 29 May 2019
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-gmm3-34hf-wcmj

## What is CVE-2018-20160?

CVE-2018-20160 is a critical vulnerability in Synacor Zimbra Collaboration Suite, published on 29 May 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ZxChat (aka ZeXtras Chat), as used for zimbra-chat and zimbra-talk in Synacor Zimbra Collaboration Suite 8.7 and 8.8 and in other products, allows XXE attacks, as demonstrated by a crafted XML request to mailboxd.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2018-20160?

It affects 1 product.


Products: Synacor Zimbra Collaboration Suite.

## How do I fix CVE-2018-20160?

No fix has been published for CVE-2018-20160 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-20160 being exploited?

There is no known exploitation of CVE-2018-20160 in the wild and no public exploit code.

## Other vulnerabilities in Synacor Zimbra Collaboration Suite

- [CVE-2024-45519](https://insights.sbomify.com/CVE-2024-45519/): Synacor Zimbra Collaboration Suite (ZCS) Command Execution (critical 10.0, exploited in the wild)
- [CVE-2022-41352](https://insights.sbomify.com/CVE-2022-41352/): Synacor Zimbra Collaboration Suite (ZCS) Arbitrary File Upload (critical 9.8, exploited in the wild)
- [CVE-2022-37042](https://insights.sbomify.com/CVE-2022-37042/): Synacor Zimbra Collaboration Suite (ZCS) Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2022-27924](https://insights.sbomify.com/CVE-2022-27924/): Synacor Zimbra Collaboration Suite (ZCS) Command Injection (critical 9.8, exploited in the wild)
- [CVE-2020-7796](https://insights.sbomify.com/CVE-2020-7796/): Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-20160 and fix it if it is affected.

What it is: CVE-2018-20160 is a critical vulnerability in Synacor Zimbra Collaboration Suite, published on 29 May 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-20160 in the wild and no public exploit code.

Affected product: Synacor 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-2018-20160/ (Markdown: https://insights.sbomify.com/CVE-2018-20160/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-20160
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-20160
- OSV: https://osv.dev/vulnerability/CVE-2018-20160

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-20160/
Summaries are generated and may contain mistakes; the official description above is the record.