---
id: "CVE-2026-121253"
kind: "vulnerability"
aliases: ["CVE-2026-121253"]
title: "Chrome: DevTools flaw lets a crafted extension bypass site isolation"
severity: "low"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["chrome", "desktop-browsers", "runtime"]
not_affected_if: ["chrome-updated", "extensions-restricted"]
published_at: "2026-11-03T21:17:36+00:00"
first_seen_at: "2026-11-03T21:19:29+00:00"
updated_at: "2026-11-03T21:20:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121253", "first_seen_at": "2026-11-03T21:19:29+00:00"}]
---

# Chrome: DevTools flaw lets a crafted extension bypass site isolation

A missing authorization check in Chrome's DevTools lets a remote attacker, using social engineering and a crafted Chrome extension, bypass site isolation. Chromium rates the severity Low.

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

## How to check

- Check the Chrome version: open `chrome://settings/help` and compare against `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

- 2026-11-03T21:19:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121253

## From the sources

Missing authorization in DevTools in Google Chrome prior to 157.0.8103.38 allowed a remote attacker leveraging social engineering to bypass site isolation via a crafted Chrome extension. (Chromium security severity: Low)

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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_