---
id: "CVE-2026-121108"
kind: "vulnerability"
aliases: ["CVE-2026-121108"]
title: "Chrome: BackgroundFetch confused deputy lets a web page bypass origin policy"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["browsers", "chrome", "package", "web"]
not_affected_if: ["chromium-version-current"]
published_at: "2026-11-03T21:17:17+00:00"
first_seen_at: "2026-11-03T21:19:15+00:00"
updated_at: "2026-11-03T21:25:12+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121108", "first_seen_at": "2026-11-03T21:19:15+00:00"}]
---

# Chrome: BackgroundFetch confused deputy lets a web page bypass origin policy

Google Chrome versions before 157.0.8103.38 have a confused deputy flaw in the BackgroundFetch feature. A remote attacker can use a crafted HTML page to potentially bypass web origin policy.

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

## How to check

- Check the installed Chrome version in Chrome's About page (chrome://settings/help)
- Compare the installed version against `157.0.8103.38`

## Fix

- Google Chrome: move to `157.0.8103.38` or later

## Timeline

- 2026-11-03T21:19:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121108

## From the sources

Confused deputy in BackgroundFetch in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to potentially bypass web origin policy via a crafted HTML page. (Chromium security severity: Medium)

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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_