---
id: GHSA-486p-g8x4-77mg
title: >-
  Duplicate Advisory: ONNX: TOCTOU arbitrary file read/write in
  save_external_dat 
summary: >-
  Duplicate Advisory: ONNX: TOCTOU arbitrary file read/write in
  save_external_dat 
severity: medium
cvss: 7.1
cwe:
  - CWE-22
vendor: onnx
product: onnx
ecosystem: pip
affected:
  - onnx <= 1.20.1
published: '2026-08-21'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T20:57:30Z'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-486p-g8x4-77mg'
references:
  - url: 'https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-49114'
  - url: >-
      https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-49114'
  - url: 'https://github.com/advisories/GHSA-486p-g8x4-77mg'
tags:
  - ghsa
  - pip
ingestedAt: '2026-09-08T21:11:12.321Z'
---

## Overview

## Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-q56x-g2fj-4rj6. This link is maintained to preserve external references.

## Original Description
In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs. Fixed in 1.21.0.

## Affected packages

- `onnx <= 1.20.1`

## Remediation

Refer to the advisory for the patched release.