---
id: "CVE-2026-124863"
page: "https://infrastack.ai/live/CVE-2026-124863"
kind: "vulnerability"
aliases: ["CVE-2026-124863"]
title: "Firefox: use-after-free in HTML parser can crash or be exploited"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "runtime"]
not_affected_if: ["up-to-date-firefox"]
published_at: "2026-11-10T14:17:18+00:00"
first_seen_at: "2026-11-10T14:22:14+00:00"
updated_at: "2026-11-10T14:26:33+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124863", "first_seen_at": "2026-11-10T14:22:14+00:00"}]
exploit_sources: []
---

# Firefox: use-after-free in HTML parser can crash or be exploited

Link for people: https://infrastack.ai/live/CVE-2026-124863 (this .md is for agents)

Firefox's HTML parser frees memory that is still referenced, a use-after-free bug. The sources do not say what an attacker can achieve beyond memory corruption.

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

## How to check

- Check the Firefox version with Help > About Firefox, or `firefox --version`
- Compare it against the fixed versions: Firefox 160, Firefox ESR 115.45, Firefox ESR 153.7

## Fix

- Firefox `160`
- Firefox ESR `115.45`
- Firefox ESR `153.7`

## Timeline

- 2026-11-10T14:22:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124863

## From the sources

Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 160, Firefox ESR 115.45, 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_