---
id: "CVE-2026-111855"
kind: "vulnerability"
aliases: ["CVE-2026-111855"]
title: "Tektronix 3 Series MDO: path traversal in web interface reads arbitrary files"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "mdo", "tektronix", "test-equipment", "web-management-interface"]
not_affected_if: ["firmware-1.21.1-or-later", "no-network-exposure"]
published_at: "2026-10-17T02:17:18+00:00"
first_seen_at: "2026-10-23T21:57:14+00:00"
updated_at: "2026-10-25T03:24:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111855", "first_seen_at": "2026-10-23T21:57:14+00:00"}]
---

# Tektronix 3 Series MDO: path traversal in web interface reads arbitrary files

Tektronix 3 Series MDO oscilloscopes before firmware 1.21.1 have a path traversal flaw in their web management interface. A remote attacker can read arbitrary files the application can access, and depending on configuration this may not require logging in.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed firmware version on the device (the sources do not say where in the interface; unknown)
- Check whether the web management interface is reachable from untrusted networks (unknown)

## Fix

- Update Tektronix 3 Series MDO firmware to `1.21.1` or later
- Restrict access to the web management interface to trusted management networks until updated

## Timeline

- 2026-10-23T21:57:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111855

## From the sources

An issue was discovered on Tektronix 3 Series MDO devices before 1.21.1. A path traversal vulnerability exists in the web management interface of the device. Insufficient validation of user-supplied file paths allows remote attackers to read arbitrary files accessible to the application. Depending on configuration, exploitation may be possible without authentication.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_