---
id: "CVE-2026-121031"
kind: "vulnerability"
aliases: ["CVE-2026-121031"]
title: "Chrome: PDF viewer flaw lets a crafted extension bypass web origin policy"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browser", "chrome", "desktop", "runtime"]
not_affected_if: ["chrome-updated", "no-malicious-extensions"]
published_at: "2026-11-03T21:17:06+00:00"
first_seen_at: "2026-11-03T21:19:08+00:00"
updated_at: "2026-11-03T21:27:37+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121031", "first_seen_at": "2026-11-03T21:19:08+00:00"}]
---

# Chrome: PDF viewer flaw lets a crafted extension bypass web origin policy

Google Chrome versions before 157.0.8103.38 have a missing authorization check in the PDF component. A remote attacker can use a crafted Chrome extension to get around web origin policy and reach a privileged page.

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

## How to check

- Check the installed Chrome version at chrome://settings/help and compare it with `157.0.8103.38`.
- Review installed extensions at chrome://extensions for anything unexpected.

## Fix

- Google Chrome: move to `157.0.8103.38` or later.

## Timeline

- 2026-11-03T21:19:08+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121031

## From the sources

Missing authorization in PDF in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to bypass web origin policy into a privileged page via a crafted Chrome extension. (Chromium security severity: Medium)

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