Cisco ThousandEyes Endpoint Agent for Windows Arbitrary File Delete Vulnerabilities

TL;DR 📌

• Multiple vulnerabilities in the update process of Cisco ThousandEyes Endpoint Agent for Windows could allow an authenticated, local attacker to delete arbitrary files on an affected device. These vulnerabilities are due to improper access controls on files that are in the local file system. An attacker could exploit these vulnerabilities by using a symbolic link to perform an agent upgrade…
• No fixed release listed yet; apply mitigations and monitor.
• Workarounds are documented in the advisory.
• CVEs: CVE-2025-20259.

What happened 🕵️‍♂️

Multiple vulnerabilities in the update process of Cisco ThousandEyes Endpoint Agent for Windows could allow an authenticated, local attacker to delete arbitrary files on an affected device.

These vulnerabilities are due to improper access controls on files that are in the local file system. An attacker could exploit these vulnerabilities by using a symbolic link to perform an agent upgrade that redirects the delete operation of any protected file. A successful exploit could allow the attacker to delete arbitrary files from the file system of the affected device.

Cisco has released software updates that address these vulnerabilities. There are no workarounds that address these vulnerabilities.

Affected products 🖥️

At the time of publication, these vulnerabilities affected Cisco ThousandEyes Endpoint Agent for Windows, regardless of device configuration.

For information about which Cisco software releases were vulnerable at the time of publication, see the Fixed Software ["#fs"] section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.

Fixed software 🔧

Upgrade to the first fixed release in your train (or later):

Workarounds 🧯

There are no workarounds that address these vulnerabilities.

Risk in context 🎯

Use vendor CVSS for prioritization. Consider exposure and asset criticality.

Fast facts ⚡

• Advisory: cisco-sa-te-endagent-filewrt-zNcDqNRJ
• Initial release: 2025-06-04T16:00:00 UTC
• Last updated: 2025-06-04T16:00:00 UTC

For leadership 🧭

Executive summary. Machines running the ThousandEyes Endpoint Agent for Windows are exposed to a local privilege issue where a logged-in user can cause the agent’s upgrade routine to delete files outside its own folder, potentially damaging the system. This is rated medium severity and requires local access, so it should be scheduled into the next patch cycle rather than treated as an emergency.

Why it matters:

• The flaw sits in the upgrade routine of the ThousandEyes Endpoint Agent for Windows, not in a network-facing service, so exploitation requires an existing local session on the endpoint.
• A symbolic link swapped in ahead of an agent upgrade can redirect the delete operation, letting an authenticated user remove files well outside the agent’s install directory.
• Any endpoint running this agent is affected regardless of configuration, meaning fleet-wide Windows deployments of the agent all carry the same exposure until patched.
• No workaround is available, so the only route to closing the gap is upgrading the agent software itself.

Now / Next / Later:

• Now: Identify every Windows host running the ThousandEyes Endpoint Agent and restrict local logon rights on those machines to trusted accounts only, since no workaround exists.
• Next: Schedule an upgrade of the ThousandEyes Endpoint Agent for Windows to the fixed release identified in Cisco’s advisory across all affected endpoints in your next maintenance window.
• Later: Add agent upgrade processes to your standard hardening review, checking that update routines validate file paths and reject symbolic link redirection before they run with elevated privileges.