---
id: "CVE-2026-124950"
page: "https://infrastack.ai/live/CVE-2026-124950"
kind: "vulnerability"
aliases: ["CVE-2026-124950"]
title: "Firefox: CSS parsing flaw lets pages bypass same-origin protection"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: [{"name": "Firefox", "fixed": [], "affected": "", "ecosystem": "runtime"}]
ecosystems: ["runtime"]
tags: ["browser", "firefox", "runtime"]
not_affected_if: ["firefox-160-or-later"]
published_at: "2026-11-10T14:17:29+00:00"
first_seen_at: "2026-11-10T14:22:20+00:00"
updated_at: "2026-11-10T14:23:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124950", "first_seen_at": "2026-11-10T14:22:20+00:00"}]
exploit_sources: []
---

# Firefox: CSS parsing flaw lets pages bypass same-origin protection

Link for people: https://infrastack.ai/live/CVE-2026-124950 (this .md is for agents)

A flaw in Firefox's CSS parsing and computation component allows a same-origin policy bypass, letting content read data across site boundaries. The description states it was fixed in Firefox 160.

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

## Affected

- runtime:Firefox affected range not listed fixed no fixed version listed

## How to check

- Check the installed Firefox version in Help > About Firefox, or run `firefox --version` on the command line.
- Versions below `160` are the ones the description names as fixed in 160.

## Fix

- Firefox `160` (the fixed release named in the description).

## Timeline

- 2026-11-10T14:22:20+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124950

## From the sources

Same-origin policy bypass in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 160.

---

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