CVE-2026-111854 in 3 MDO
Summary
by MITRE • 10/17/2026
An issue was discovered on Tektronix 3 Series MDO devices before 1.21.1. A path traversal vulnerability in the SCPI FILESystem command interface allows remote attackers to read or modify arbitrary files on the device through insufficient validation of file paths supplied to filesystem access commands.
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Analysis
by VulDB Data Team • 10/17/2026
The discovery of a path traversal vulnerability within Tektronix 3 Series Mixed Domain Oscilloscopes (MDO) prior to version 1.21.1 represents a significant security flaw in the instrument's command interface architecture. This specific weakness resides in the SCPI Standard Commands for Programmable Instruments FILESystem command set, which is designed to facilitate file management operations such as reading, writing, and navigating directories on the device’s internal storage or connected USB drives. The core technical failure lies in the insufficient validation of user-supplied file paths before they are processed by the underlying operating system functions. When a remote attacker issues a SCPI command containing directory traversal sequences, typically represented by dot-dot-slash characters such as ../, the firmware fails to sanitize these inputs effectively. Consequently, instead of restricting access to the intended application-specific directories, the device resolves the path relative to the root file system or other sensitive locations outside the sandboxed environment where oscilloscope data and configuration files are normally stored.
This lack of input validation allows an authenticated remote attacker to perform unauthorized read operations on arbitrary files residing on the device. By navigating up directory levels from a permitted location, an adversary can access critical system configurations, user credentials, or proprietary calibration data that should remain isolated from general application logic. Furthermore, the vulnerability extends beyond mere information disclosure; it permits the modification of these arbitrary files if write permissions are granted to the executing context. This capability enables an attacker to overwrite configuration files, potentially altering device behavior, disabling security logging mechanisms, or injecting malicious scripts into startup sequences. The impact is severe because oscilloscopes in industrial and research environments often handle sensitive measurement data and may be connected to networks that require strict integrity controls. Compromising the file system can lead to a complete loss of trust in the instrument's output accuracy if calibration constants are tampered with, or result in persistent unauthorized access through backdoor configurations.
From an industry standard perspective, this vulnerability aligns directly with CWE-22: Improper Limitation of a Pathname to a Restricted Directory, which categorizes flaws where software does not properly neutralize special elements within file paths that can cause the path to resolve outside of the intended restricted directory. In terms of offensive security frameworks, this exploitation technique maps to ATT&CK T1083: File and Directory Discovery for reconnaissance purposes if used solely for reading files, or more critically to T1562: Impair Defenses when attackers modify configuration settings to disable monitoring tools. The attack vector is classified as remote with low complexity but requires authentication, highlighting that while the network exposure increases risk, the prerequisite of valid credentials limits immediate exploitation by unauthenticated actors on public networks. However, in segmented laboratory or industrial control environments where internal trust boundaries are often relaxed for convenience, this threat becomes highly actionable.
Mitigation strategies must prioritize both technical remediation and operational hardening. The primary defense is to apply the vendor-supplied firmware update that addresses version 1.21.1 immediately across all affected devices in the inventory. This patch introduces proper input sanitization routines within the SCPI parser, ensuring that any path traversal sequences are detected and rejected before reaching the file system layer. In environments where immediate patching is not feasible due to operational constraints, network segmentation should be enforced to restrict access to the oscilloscope’s management interface exclusively from trusted administrative subnets. Additionally, implementing strict firewall rules that limit SCPI port accessibility can reduce the attack surface significantly. Administrators should also enforce strong authentication policies and consider disabling unused remote interfaces if they are not actively required for automated workflows, thereby reducing opportunities for exploitation by compromised credentials or insider threats.