---
id: "CVE-2026-124889"
page: "https://infrastack.ai/live/CVE-2026-124889"
kind: "vulnerability"
aliases: ["CVE-2026-124889"]
title: "Firefox: CSS parsing use-after-free could let a page run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browser", "firefox", "runtime"]
not_affected_if: ["firefox-160-or-later", "firefox-esr-153.7-or-later"]
published_at: "2026-11-10T14:17:22+00:00"
first_seen_at: "2026-11-10T14:22:15+00:00"
updated_at: "2026-11-10T14:26:03+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124889", "first_seen_at": "2026-11-10T14:22:15+00:00"}]
exploit_sources: []
---

# Firefox: CSS parsing use-after-free could let a page run code

Link for people: https://infrastack.ai/live/CVE-2026-124889 (this .md is for agents)

A use-after-free bug in Firefox's CSS Parsing and Computation component lets memory be reused after it is freed. The sources do not state what an attacker can do beyond that, so the impact is not confirmed.

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

## How to check

- Check the Firefox version under Help > About Firefox, or `firefox --version` on the command line.
- Compare it against the fixed versions named in the sources: Firefox 160 and Firefox ESR 153.7.

## Fix

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

## Timeline

- 2026-11-10T14:22:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124889

## From the sources

Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

---

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