# CVE-2019-20104: XML external entity in Crowd

> Remote attackers can cause a Denial of Service in Atlassian Crowd via XML Entity Expansion in the OpenID client.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 6 Feb 2020
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-g2rw-3cc4-qq38

## What is CVE-2019-20104?

CVE-2019-20104 is a high-severity vulnerability in Atlassian Crowd, published on 6 Feb 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The OpenID client application in Atlassian Crowd before version 3.6.2, and from version 3.7.0 before 3.7.1 allows remote attackers to perform a Denial of Service attack via an XML Entity Expansion vulnerability.

Weakness: CWE-776 (Improper Restriction of Recursive Entity References in DTDs)

## Which versions are affected by CVE-2019-20104?

It affects 1 product.


Products: Atlassian Crowd.

## How do I fix CVE-2019-20104?

No fix has been published for CVE-2019-20104 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-20104 being exploited?

There is no known exploitation of CVE-2019-20104 in the wild and no public exploit code.

## Other vulnerabilities in Atlassian Crowd

- [CVE-2019-11580](https://insights.sbomify.com/CVE-2019-11580/): Atlassian Crowd and Crowd Data Center Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2022-43782](https://insights.sbomify.com/CVE-2022-43782/): Auth bypass in Crowd Data Center (critical 9.8)
- [CVE-2016-6496](https://insights.sbomify.com/CVE-2016-6496/): Deserialization in n/a (critical 9.8)
- [CVE-2017-18105](https://insights.sbomify.com/CVE-2017-18105/): Auth bypass in Crowd (high 8.1)
- [CVE-2018-20238](https://insights.sbomify.com/CVE-2018-20238/): Auth bypass in Crowd (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-20104 and fix it if it is affected.

What it is: CVE-2019-20104 is a high-severity vulnerability in Atlassian Crowd, published on 6 Feb 2020. 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-2019-20104 in the wild and no public exploit code.

Affected product: Atlassian Crowd. 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-2019-20104/ (Markdown: https://insights.sbomify.com/CVE-2019-20104/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-20104
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-20104
- OSV: https://osv.dev/vulnerability/CVE-2019-20104

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-20104/
Summaries are generated and may contain mistakes; the official description above is the record.