Cisco ThousandEyes Endpoint Agent for Windows Arbitrary File Delete Vulnerabilities

🚨SEVERITY: MEDIUM — CVSS 5.3Security Advisory

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…
  • Highest CVSS: 5.3 (Medium).
  • Check the advisory for fixed releases — remediation detail is in the vendor link below.
  • CVEs: CVE-2025-20259.

What it is

CVE-2025-20259 affects the update process of Cisco ThousandEyes Endpoint Agent for Windows. It’s a local privilege issue rather than a remote one: exploitation requires an authenticated, local attacker on the Windows host running the agent.

The root cause is improper access controls on local files during agent upgrades. An attacker can place a symbolic link so that when the agent performs an upgrade, the delete operation intended for an agent-owned file is redirected to a different, protected file on the system. The result is arbitrary file deletion elsewhere on the filesystem, carried out with whatever privileges the upgrade process runs under.

This is scoped to the Windows build of the Endpoint Agent. Cisco has confirmed the macOS and RoomOS versions of the Endpoint Agent are not affected. There is no data-plane or network exposure here — the attack path runs entirely through local access to the machine and the agent’s update mechanism.

CVSS is 5.3 (Medium), reflecting the local, authenticated, low-complexity nature of the attack and the impact being limited to confidentiality, integrity and availability at a low level (file deletion) rather than code execution.

What to do

  • Upgrade Cisco ThousandEyes Endpoint Agent for Windows to release 2.3.3, which is the first fixed release. Anything earlier than 2.3.3 is listed as vulnerable.
  • There are no workarounds — this needs the version upgrade, not a configuration change.
  • Since exploitation requires local authenticated access, review which users have local logon rights on machines running the Endpoint Agent, particularly on shared or multi-user Windows endpoints.
  • No action needed for ThousandEyes Endpoint Agent on macOS or RoomOS — Cisco has confirmed these are not affected.

For leadership 🧭

Executive summary. Any Windows endpoint running ThousandEyes Endpoint Agent before version 2.3.3 can have arbitrary files deleted by a local, authenticated user who abuses the upgrade process’s symbolic-link handling. There’s no workaround, so this needs scheduling into a patch cycle rather than urgent emergency action, but shared or multi-user Windows hosts should move sooner.

Why it matters:

  • The flaw sits in the agent’s own upgrade mechanism, so any Windows machine running ThousandEyes Endpoint Agent is exposed regardless of how it’s configured.
  • A local, authenticated attacker can use a symbolic link to redirect the upgrade’s file-delete step onto a protected system file, running with whatever privilege the upgrade process holds.
  • Shared or multi-user Windows endpoints carry the greatest risk since more than one local account may have the access needed to trigger the redirect.
  • macOS and RoomOS builds of the Endpoint Agent are confirmed unaffected, so remediation effort can focus solely on the Windows fleet.

Now / Next / Later:

  • Now: Identify every Windows host running ThousandEyes Endpoint Agent and check the installed version against 2.3.3.
  • Next: Upgrade all affected Windows agents to release 2.3.3 in the next available change window, since no workaround exists.
  • Later: Review local logon rights on Windows machines running the agent, especially shared or multi-user endpoints, to limit who can trigger the upgrade process.

Source