---
id: "CVE-2026-117869"
kind: "vulnerability"
aliases: ["CVE-2026-117869"]
title: "Firefox: use-after-free in DOM core and HTML lets a page run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["browser", "desktop", "firefox", "package"]
not_affected_if: ["already-on-fixed-version"]
published_at: "2026-10-27T14:16:41+00:00"
first_seen_at: "2026-10-27T14:32:21+00:00"
updated_at: "2026-10-27T14:39:15+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117869", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: use-after-free in DOM core and HTML lets a page run code

A use-after-free bug in the Firefox DOM Core and HTML component lets memory be reused after it is freed. The sources do not say what an attacker can get beyond that; Mozilla fixed it in Firefox 159, ESR 115.44 and ESR 153.6.

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

## How to check

- Run `firefox --version` or open the About Firefox page and compare against `159`, `115.44` or `153.6`
- On managed fleets, check the installed Firefox ESR version against `115.44` or `153.6`

## Fix

- Update Firefox to `159` or later
- Update Firefox ESR to `115.44` or `153.6`

## Timeline

- 2026-10-27T14:32:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117869

## From the sources

Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.

---

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