# CVE-2016-6876: Denial of service in n/a

> Remote DNS servers can cause a denial of service via crafted PTR responses, affecting F5 BIG-IP systems.

- **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 Sep 2016
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-mmx7-r9x5-783v

## What is CVE-2016-6876?

CVE-2016-6876 is a high-severity denial of service vulnerability in F5 Big-Ip Access Policy Manager, published on 7 Sep 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The RESOLV::lookup iRule command in F5 BIG-IP LTM, APM, ASM, and Link Controller 10.2.1 through 10.2.4, 11.2.1, 11.4.x, 11.5.x before 11.5.4 HF2, 11.6.x before 11.6.1, and 12.0.0 before HF3; BIG-IP AAM, AFM, and PEM 11.4.x, 11.5.x before 11.5.4 HF2, 11.6.x before 11.6.1, and 12.0.0 before HF3; BIG-IP Analytics 11.2.1, 11.4.x, 11.5.x before 11.5.4 HF2, 11.6.x before 11.6.1, and 12.0.0 before HF3; BIG-IP DNS 12.0.0 before HF3; BIG-IP Edge Gateway, WebAccelerator, and WOM 10.2.1 through 10.2.4 and 11.2.1; BIG-IP GTM 10.2.1 through 10.2.4, 11.2.1, 11.4.x, 11.5.x before 11.5.4 HF2, and 11.6.x before 11.6.1; and BIG-IP PSM 10.2.1 through 10.2.4 and 11.4.0 through 11.4.1 allows remote DNS servers to cause a denial of service (CPU consumption or Traffic Management Microkernel crash) via a crafted PTR response.

Weakness: CWE-399

## Which versions are affected by CVE-2016-6876?

It affects 14 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 Global Traffic Manager, F5 Big-Ip Link Controller, F5 Big-Ip Local Traffic Manager, F5 Big-Ip Policy Enforcement Manager, F5 Big-Ip Protocol Security Module, F5 Big-Ip Wan Optimization Manager, F5 Big-Ip Webaccelerator.

## How do I fix CVE-2016-6876?

No fix has been published for CVE-2016-6876 yet. Limit exposure of the affected software until one is available.

## Is CVE-2016-6876 being exploited?

There is no known exploitation of CVE-2016-6876 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-2016-6876 and fix it if it is affected.

What it is: CVE-2016-6876 is a high-severity denial of service vulnerability in F5 Big-Ip Access Policy Manager, published on 7 Sep 2016. 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-2016-6876 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-2016-6876/ (Markdown: https://insights.sbomify.com/CVE-2016-6876/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2016-6876
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-6876
- OSV: https://osv.dev/vulnerability/CVE-2016-6876

---
From sbomify Insights: https://insights.sbomify.com/CVE-2016-6876/
Summaries are generated and may contain mistakes; the official description above is the record.