# CVE-2021-21399: Unauthenticated SubSonic backend access in Ampache

> Unauthenticated attackers can access the SubSonic backend in Ampache by using a non-existent username, bypassing authentication checks.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 13 Apr 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-p9pm-j95j-5mjf, UBUNTU-CVE-2021-21399

## What is CVE-2021-21399?

CVE-2021-21399 is a critical authentication bypass vulnerability in ampache, published on 13 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Ampache is a web based audio/video streaming application and file manager. Versions prior to 4.4.1 allow unauthenticated access to Ampache using the subsonic API. To successfully make the attack you must use a username that is not part of the site to bypass the auth checks. For more details and workaround guidance see the referenced GitHub security advisory.

Weakness: CWE-287 (Improper Authentication), CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2021-21399?

It affects 1 product.


Products: Ampache Ampache.

## How do I fix CVE-2021-21399?

No fix has been published for CVE-2021-21399 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21399 being exploited?

There is no known exploitation of CVE-2021-21399 in the wild and no public exploit code.

## Other vulnerabilities in ampache

- [CVE-2023-0606](https://insights.sbomify.com/CVE-2023-0606/): Cross-site Scripting (XSS) - Reflected in ampache/ampache (critical 9.3)
- [CVE-2019-12385](https://insights.sbomify.com/CVE-2019-12385/): SQL injection in n/a (high 8.8)
- [CVE-2017-18375](https://insights.sbomify.com/CVE-2017-18375/): Deserialization in n/a (high 8.8)
- [CVE-2020-15153](https://insights.sbomify.com/CVE-2020-15153/): Unauthenticated SQL injection in Ampache (high 8.2)
- [CVE-2006-5668](https://insights.sbomify.com/CVE-2006-5668/): Auth bypass in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21399 and fix it if it is affected.

What it is: CVE-2021-21399 is a critical authentication bypass vulnerability in ampache, published on 13 Apr 2021. 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-2021-21399 in the wild and no public exploit code.

Affected product: ampache. 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-2021-21399/ (Markdown: https://insights.sbomify.com/CVE-2021-21399/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21399
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21399
- OSV: https://osv.dev/vulnerability/CVE-2021-21399

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21399/
Summaries are generated and may contain mistakes; the official description above is the record.