# CVE-2019-6638: Denial of service in BIG-IP

> Attackers can cause a denial of service on F5 BIG-IP devices by sending malformed HTTP requests to an iControl REST endpoint, triggering an infinite loop.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Jul 2019
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-jmww-463h-74hc

## What is CVE-2019-6638?

CVE-2019-6638 is a medium-severity denial of service vulnerability in F5 Big-Ip Access Policy Manager, published on 3 Jul 2019. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

On BIG-IP 14.1.0-14.1.0.5 and 14.0.0-14.0.0.4, Malformed http requests made to an undisclosed iControl REST endpoint can lead to infinite loop of the restjavad process.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2019-6638?

It affects 13 products.


Products: F5 Big-Ip Access Policy Manager, F5 Big-Ip Advanced Firewall Manager, F5 Big-Ip Analytics, F5 Big-Ip Application Acceleration Manager, F5 Big-Ip Application Security Manager, F5 Big-Ip Domain Name System, F5 Big-Ip Edge Gateway, F5 Big-Ip Fraud Protection Service, F5 Big-Ip Global Traffic Manager, F5 Big-Ip Link Controller, F5 Big-Ip Local Traffic Manager, F5 Big-Ip Policy Enforcement Manager, F5 Big-Ip Webaccelerator.

## How do I fix CVE-2019-6638?

No fix has been published for CVE-2019-6638 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-6638 being exploited?

There is no known exploitation of CVE-2019-6638 in the wild and no public exploit code.

## Other vulnerabilities in F5 Big-Ip Access Policy Manager

- [CVE-2023-46747](https://insights.sbomify.com/CVE-2023-46747/): F5 BIG-IP Configuration Utility Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2022-1388](https://insights.sbomify.com/CVE-2022-1388/): F5 BIG-IP Missing Authentication (critical 9.8, exploited in the wild)
- [CVE-2021-22986](https://insights.sbomify.com/CVE-2021-22986/): F5 BIG-IP and BIG-IQ Centralized Management iControl REST Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2021-22991](https://insights.sbomify.com/CVE-2021-22991/): F5 BIG-IP Traffic Management Microkernel Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2020-5902](https://insights.sbomify.com/CVE-2020-5902/): F5 BIG-IP Traffic Management User Interface (TMUI) Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-6638 and fix it if it is affected.

What it is: CVE-2019-6638 is a medium-severity denial of service vulnerability in F5 Big-Ip Access Policy Manager, published on 3 Jul 2019. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-6638 in the wild and no public exploit code.

Affected product: F5 Big-Ip Access Policy Manager. 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-2019-6638/ (Markdown: https://insights.sbomify.com/CVE-2019-6638/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-6638
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-6638
- OSV: https://osv.dev/vulnerability/CVE-2019-6638

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-6638/
Summaries are generated and may contain mistakes; the official description above is the record.