# CVE-2016-2167: Auth bypass in n/a

> Remote attackers can bypass authentication and access restricted repositories by exploiting a prefix matching flaw in Cyrus SASL realm validation.

- **Severity:** Medium 6.8 (`CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 May 2016
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2016-2167, GHSA-4j43-22vc-mh3h, UBUNTU-CVE-2016-2167

## What is CVE-2016-2167?

CVE-2016-2167 is a medium-severity authentication bypass vulnerability in n/a, published on 5 May 2016. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The canonicalize_username function in svnserve/cyrus_auth.c in Apache Subversion before 1.8.16 and 1.9.x before 1.9.4, when Cyrus SASL authentication is used, allows remote attackers to authenticate and bypass intended access restrictions via a realm string that is a prefix of an expected repository realm string.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2016-2167?

It affects 1 product.


Products: Apache Subversion.

## How do I fix CVE-2016-2167?

Upgrade to a fixed version.

## Is CVE-2016-2167 being exploited?

There is no known exploitation of CVE-2016-2167 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2017-9800](https://insights.sbomify.com/CVE-2017-9800/): A maliciously constructed svn+ssh:// URL would cause Subversion clients before 1.8.19, 1.9.x before 1.9.7, and 1.10.0.x through 1.10.0-alpha (critical 9.8)
- [CVE-2013-4246](https://insights.sbomify.com/CVE-2013-4246/): Denial of service in n/a (high 8.8)
- [CVE-2015-5259](https://insights.sbomify.com/CVE-2015-5259/): Integer overflow in n/a (high 8.6)
- [CVE-2024-45720](https://insights.sbomify.com/CVE-2024-45720/): Apache Subversion: Command line argument injection on Windows platforms (high 8.2)
- [CVE-2015-0202](https://insights.sbomify.com/CVE-2015-0202/): Denial of service in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2016-2167 and fix it if it is affected.

What it is: CVE-2016-2167 is a medium-severity authentication bypass vulnerability in n/a, published on 5 May 2016. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2016-2167 in the wild and no public exploit code.

Affected product: n/a. 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-2016-2167/ (Markdown: https://insights.sbomify.com/CVE-2016-2167/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-2167
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-2167
- OSV: https://osv.dev/vulnerability/CVE-2016-2167

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From sbomify Insights: https://insights.sbomify.com/CVE-2016-2167/
Summaries are generated and may contain mistakes; the official description above is the record.