CVE-2026-118683 in Monai
Summary
by MITRE • 10/28/2026
MONAI from 1.2.0 before 1.6.1 contains a remote code execution vulnerability in ConfigWorkflow.__init__, which passes a bundle's configs/logging.conf to logging.config.fileConfig that eval()s handler class and args fields. Attackers can publish a malicious bundle whose logging.conf runs arbitrary Python at workflow construction when a victim loads or runs the bundle.
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified in MONAI versions prior to 1.6.1 represents a critical remote code execution flaw rooted in improper neutralization of special elements during configuration processing. Specifically, the issue resides within the ConfigWorkflow initialization routine, which is responsible for loading and applying configuration files associated with medical imaging bundles. When a user loads or executes such a bundle, the system invokes logging.config.fileConfig to parse the provided logging.conf file. This standard Python library function supports dynamic class instantiation through its handler definitions, allowing developers to specify custom log handlers by providing fully qualified class names and their initialization arguments within the configuration structure.
The core technical flaw arises because MONAI passes user-supplied or bundle-provided content directly into this parsing mechanism without sufficient sanitization of the handler class and argument fields. The logging.config.fileConfig function internally utilizes Python's eval-like mechanisms to instantiate these classes. Consequently, if an attacker publishes a malicious bundle containing a crafted logging.conf file, they can inject arbitrary Python code within the handler configuration parameters. When a victim loads this bundle, the initialization process triggers the execution of this injected code during the workflow construction phase, effectively granting the attacker remote code execution capabilities on the victim's system without any additional interaction or authentication beyond loading the malicious artifact.
This vulnerability aligns with CWE-94, commonly known as Improper Control of Generation of Code (Code Injection), specifically involving the use of unsafe evaluation functions that process untrusted input. From a tactical perspective, this attack vector corresponds to ATT&CK technique T1059, Command and Scripting Interpreter, where an adversary uses system utilities or interpreters like Python to execute commands. The impact is severe as it allows for complete compromise of the host environment running MONAI, potentially leading to data exfiltration, lateral movement within a networked research infrastructure, or disruption of critical medical imaging workflows.
Mitigation strategies must prioritize immediate version updates and strict input validation practices. Users should upgrade their MONAI installations to version 1.6.1 or later, where this specific code path has been secured against arbitrary execution during configuration loading. In environments where upgrading is not immediately feasible, administrators should implement rigorous bundle verification protocols, ensuring that all logging configurations are validated against a whitelist of allowed handler classes and parameters before being passed to the configuration parser. Additionally, adopting principle of least privilege for user accounts running MONAI can limit the potential damage if such an execution were to occur in legacy systems.