---
id: "CVE-2026-118684"
kind: "vulnerability"
aliases: ["CVE-2026-118684"]
title: "MONAI: hash check silently passes when no hash given, enabling file substitution"
severity: "high"
cvss: 8.2
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["medical-imaging", "ml-models", "monai", "package", "python"]
not_affected_if: ["hashes-always-supplied", "local-files-only", "version-1.6.1-or-later"]
published_at: "2026-10-28T19:17:35+00:00"
first_seen_at: "2026-10-28T19:34:55+00:00"
updated_at: "2026-10-28T19:35:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118684", "first_seen_at": "2026-10-28T19:34:55+00:00"}]
---

# MONAI: hash check silently passes when no hash given, enabling file substitution

MONAI versions before 1.6.1 have a check_hash() function that returns True without verifying anything when no expected hash is supplied. An attacker who can intercept downloads or compromise a registry can swap in malicious bundles, datasets, or model archives that are then accepted, which can lead to code execution.

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

## How to check

- Run `pip show monai` and confirm the installed version is below `1.6.1`
- Search project code and downloader calls for `check_hash(` or download helpers invoked without a `hash_val` argument

## Fix

- Upgrade MONAI to `1.6.1` or later
- Until upgraded, pass an explicit expected hash to every download and verification call so the check cannot be skipped

## Timeline

- 2026-10-28T19:34:55+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118684

## From the sources

MONAI before 1.6.1 contains an insufficient integrity verification vulnerability in check_hash() that silently returns True when hash_val is None, with MD5 as the default hash type. Attackers performing man-in-the-middle or registry compromise can substitute bundles, datasets, or model archives downloaded without hashes, enabling malicious file delivery and potential code execution.

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