# CVE-2018-5540: Privilege escalation in BIG-IP (DNS, GTM)

> The big3d process fails to minimize group privileges at startup, allowing local attackers to escalate privileges on F5 BIG-IP and related management systems.

- **Severity:** Medium 4.4 (`CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Jul 2018
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-6vp9-vc7c-884p

## What is CVE-2018-5540?

CVE-2018-5540 is a medium-severity vulnerability in F5 Big-Ip Domain Name System, published on 19 Jul 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

On F5 BIG-IP 13.0.0-13.0.1, 12.1.0-12.1.3.3, 11.6.0-11.6.3.1, or 11.5.1-11.5.6, Enterprise Manager 3.1.1, BIG-IQ Centralized Management 5.0.0-5.1.0, BIG-IQ Cloud and Orchestration 1.0.0, or F5 iWorkflow 2.1.0-2.3.0 the big3d process does not irrevocably minimize group privileges at start up.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2018-5540?

It affects 6 products.


Products: F5 Big-Ip Domain Name System, F5 Big-Ip Global Traffic Manager, F5 Big-Iq Centralized Management, F5 Big-Iq Cloud and Orchestration, F5 Enterprise Manager, F5 F5 Iworkflow.

## How do I fix CVE-2018-5540?

No fix has been published for CVE-2018-5540 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-5540 being exploited?

There is no known exploitation of CVE-2018-5540 in the wild and no public exploit code.

## Other vulnerabilities in F5 Big-Ip Domain Name System

- [CVE-2022-23013](https://insights.sbomify.com/CVE-2022-23013/): Cross-site scripting in BIG-IP DNS & GTM (high 8.8)
- [CVE-2026-40061](https://insights.sbomify.com/CVE-2026-40061/): iControl REST and tmsh vulnerability (high 8.5)
- [CVE-2022-41787](https://insights.sbomify.com/CVE-2022-41787/): BIG-IP DNS Express vulnerability CVE-2022-41787 (high 7.5)
- [CVE-2021-23032](https://insights.sbomify.com/CVE-2021-23032/): Denial of service in BIG-IP DNS (high 7.5)
- [CVE-2020-27717](https://insights.sbomify.com/CVE-2020-27717/): Denial of service in BIG-IP DNS (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-5540 and fix it if it is affected.

What it is: CVE-2018-5540 is a medium-severity vulnerability in F5 Big-Ip Domain Name System, published on 19 Jul 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-5540 in the wild and no public exploit code.

Affected product: F5 Big-Ip Domain Name System. 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-2018-5540/ (Markdown: https://insights.sbomify.com/CVE-2018-5540/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-5540
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-5540
- OSV: https://osv.dev/vulnerability/CVE-2018-5540

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-5540/
Summaries are generated and may contain mistakes; the official description above is the record.