# CVE-2017-16086: ReDoS via long UserAgent header in ua-parser

> Attackers can cause denial of service in applications using ua-parser by sending specially crafted User-Agent headers that trigger excessive CPU usage.

- **Severity:** High 7.5 (`CVSS:3.0/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:** 7 Jun 2018
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-pmg9-p9r2-6q87

## What is CVE-2017-16086?

CVE-2017-16086 is a high-severity denial of service vulnerability in HackerOne ua-parser node module, published on 7 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ua-parser is a port of Browserscope's user agent parser. ua-parser is vulnerable to a ReDoS (Regular Expression Denial of Service) attack when given a specially crafted UserAgent header.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2017-16086?

2 open source packages ship an affected version, including ua-parser. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `ua-parser` | npm | All versions to 0.3.5 | None |
| `ua-parser` | npm | All versions to 0.3.5 | None |

Products: Ua-Parser Project Ua-Parser.

## How do I fix CVE-2017-16086?

No fix has been published for CVE-2017-16086 yet. Limit exposure of the affected software until one is available.

## Is CVE-2017-16086 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2017-16086 exists.

Public exploit code:

- ua-parser-js npm module ReDoS (metasploit)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-16086 and fix it if it is affected.

What it is: CVE-2017-16086 is a high-severity denial of service vulnerability in HackerOne ua-parser node module, published on 7 Jun 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2017-16086 exists.

Affected packages and fixed versions:
- ua-parser (npm): affected all versions up to 0.3.5; no fix listed
- ua-parser (npm): affected all versions up to 0.3.5; no fix listed

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-2017-16086/ (Markdown: https://insights.sbomify.com/CVE-2017-16086/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-16086
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-16086
- OSV: https://osv.dev/vulnerability/CVE-2017-16086

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-16086/
Summaries are generated and may contain mistakes; the official description above is the record.