---
id: "CVE-2026-121161"
kind: "vulnerability"
aliases: ["CVE-2026-121161"]
title: "Chrome: BackgroundFetch flaw leaks cross-origin data from a crafted page"
severity: "medium"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "chrome", "end-users", "runtime"]
not_affected_if: ["chrome-up-to-date"]
published_at: "2026-11-03T21:17:23+00:00"
first_seen_at: "2026-11-03T21:19:23+00:00"
updated_at: "2026-11-03T21:23:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121161", "first_seen_at": "2026-11-03T21:19:23+00:00"}]
---

# Chrome: BackgroundFetch flaw leaks cross-origin data from a crafted page

A flaw in the BackgroundFetch feature of Google Chrome lets a crafted HTML page read cross-origin data it should not reach. Chromium rates it Medium severity.

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

## How to check

- Check the Chrome version in Chrome's About page or with `chrome://version`
- Confirm whether the installed version is earlier than `157.0.8103.38`

## Fix

- Google Chrome: move to `157.0.8103.38` or later

## Timeline

- 2026-11-03T21:19:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121161

## From the sources

Information leak in BackgroundFetch in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to obtain cross-origin data 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_