# CVE-2023-31421: Beats, Elastic Agent, APM Server, and Fleet Server Improper Certificate Validation issue

> Attackers can bypass TLS certificate validation when clients connect via IP address, enabling man-in-the-middle attacks against Elastic observability components.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Oct 2023
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-4x46-8gg7-f9vx

## What is CVE-2023-31421?

CVE-2023-31421 is a medium-severity vulnerability in Elastic APM Server, published on 26 Oct 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

It was discovered that when acting as TLS clients, Beats, Elastic Agent, APM Server, and Fleet Server did not verify whether the server certificate is valid for the target IP address; however, certificate signature validation is still performed. More specifically, when the client is configured to connect to an IP address (instead of a hostname) it does not validate the server certificate's IP SAN values against that IP address and certificate validation fails, and therefore the connection is not blocked as expected.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2023-31421?

It affects 4 products.


Products: Elastic Apm Server, Elastic Elastic Agent, Elastic Elastic Beats, Elastic Elastic Fleet Server.

## How do I fix CVE-2023-31421?

No fix has been published for CVE-2023-31421 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-31421 being exploited?

There is no known exploitation of CVE-2023-31421 in the wild and no public exploit code.

## Other vulnerabilities in Elastic APM Server

- [CVE-2024-37286](https://insights.sbomify.com/CVE-2024-37286/): APM Server Insertion of Sensitive Information into Log File (medium 5.7)
- [CVE-2024-23448](https://insights.sbomify.com/CVE-2024-23448/): APM Server Insertion of Sensitive Information into Log File (medium 5.7)
- [CVE-2026-78594](https://insights.sbomify.com/CVE-2026-78594/): Improper Handling of Highly Compressed Data in APM Server Leading to Persistent Denial of Service (medium 4.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-31421 and fix it if it is affected.

What it is: CVE-2023-31421 is a medium-severity vulnerability in Elastic APM Server, published on 26 Oct 2023. 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-2023-31421 in the wild and no public exploit code.

Affected product: Elastic APM Server. 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-2023-31421/ (Markdown: https://insights.sbomify.com/CVE-2023-31421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-31421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-31421
- OSV: https://osv.dev/vulnerability/CVE-2023-31421

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-31421/
Summaries are generated and may contain mistakes; the official description above is the record.