# CVE-2025-20126: Cisco ThousandEyes Endpoint Agent Certificate Validation Vulnerability

> An on-path attacker can intercept or manipulate metrics data by bypassing certificate validation in the Cisco ThousandEyes Endpoint Agent.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/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:** 8 Jan 2025
- **Updated:** 13 Jan 2025
- **Also known as:** GHSA-jwc2-hj9w-9cff

## What is CVE-2025-20126?

CVE-2025-20126 is a medium-severity vulnerability in Cisco ThousandEyes Endpoint Agent, published on 8 Jan 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in certification validation routines of Cisco ThousandEyes Endpoint Agent for macOS and RoomOS could allow an unauthenticated, remote attacker to intercept or manipulate metrics information.

This vulnerability exists because the affected software does not properly validate certificates for hosted metrics services. An on-path attacker could exploit this vulnerability by intercepting network traffic using a crafted certificate. A successful exploit could allow the attacker to masquerade as a trusted host and monitor or change communications between the remote metrics service and the vulnerable client.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2025-20126?

It affects 1 product.


Products: Cisco Thousandeyes Endpoint Agent.

## How do I fix CVE-2025-20126?

No fix has been published for CVE-2025-20126 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-20126 being exploited?

There is no known exploitation of CVE-2025-20126 in the wild and no public exploit code.

## Other vulnerabilities in Cisco ThousandEyes Endpoint Agent

- [CVE-2025-20259](https://insights.sbomify.com/CVE-2025-20259/): Cisco ThousandEyes Endpoint Agent for Windows Arbitrary File Write Vulnerability (medium 5.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-20126 and fix it if it is affected.

What it is: CVE-2025-20126 is a medium-severity vulnerability in Cisco ThousandEyes Endpoint Agent, published on 8 Jan 2025. 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-2025-20126 in the wild and no public exploit code.

Affected product: Cisco ThousandEyes Endpoint Agent. 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-2025-20126/ (Markdown: https://insights.sbomify.com/CVE-2025-20126/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-20126
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-20126
- OSV: https://osv.dev/vulnerability/CVE-2025-20126

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-20126/
Summaries are generated and may contain mistakes; the official description above is the record.