---
id: "CVE-2026-124931"
page: "https://infrastack.ai/live/CVE-2026-124931"
kind: "vulnerability"
aliases: ["CVE-2026-124931"]
title: "Firefox: DOM flaw lets pages bypass the same-origin policy"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "runtime"]
not_affected_if: ["patched-version"]
published_at: "2026-11-10T14:17:27+00:00"
first_seen_at: "2026-11-10T14:22:18+00:00"
updated_at: "2026-11-10T14:24:17+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124931", "first_seen_at": "2026-11-10T14:22:18+00:00"}]
exploit_sources: []
---

# Firefox: DOM flaw lets pages bypass the same-origin policy

Link for people: https://infrastack.ai/live/CVE-2026-124931 (this .md is for agents)

A flaw in the Core and HTML DOM component of Firefox lets a web page bypass the same-origin policy that keeps sites from reading each other's data. An attacker who gets a victim to visit a malicious page could read or act on data from other sites the victim is logged into.

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

## How to check

- Open the Firefox menu, go to Settings > General > About Firefox, and read the version shown.
- Check the installed version with `firefox --version` on Linux or macOS.

## Fix

- Firefox: move to `160` or later.
- Firefox ESR: move to `153.7` or later.

## Timeline

- 2026-11-10T14:22:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124931

## From the sources

Same-origin policy bypass in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_