# CVE-2019-16201: Denial of service in n/a

> An attacker can cause a denial of service in Ruby's WEBrick server via ReDoS in DigestAuth if the server is exposed to untrusted networks.

- **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:** Yes
- **Published:** 26 Nov 2019
- **Updated:** 5 Aug 2024
- **Also known as:** ALPINE-CVE-2019-16201, CLEANSTART-2026-BG69188, DEBIAN-CVE-2019-16201, GHSA-26h5-qgg3-p324, UBUNTU-CVE-2019-16201

## What is CVE-2019-16201?

CVE-2019-16201 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

WEBrick::HTTPAuth::DigestAuth in Ruby through 2.4.7, 2.5.x through 2.5.6, and 2.6.x through 2.6.4 has a regular expression Denial of Service cause by looping/backtracking. A victim must expose a WEBrick server that uses DigestAuth to the Internet or a untrusted network.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2019-16201?

It affects 2 products.


Products: Debian Debian Linux, Ruby-Lang Ruby.

## How do I fix CVE-2019-16201?

Upgrade to a fixed version.

## Is CVE-2019-16201 being exploited?

There is no known exploitation of CVE-2019-16201 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-16201 and fix it if it is affected.

What it is: CVE-2019-16201 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 26 Nov 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-2019-16201 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2019-16201/ (Markdown: https://insights.sbomify.com/CVE-2019-16201/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-16201
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-16201
- OSV: https://osv.dev/vulnerability/CVE-2019-16201

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-16201/
Summaries are generated and may contain mistakes; the official description above is the record.