---
id: "CVE-2026-117949"
kind: "vulnerability"
aliases: ["CVE-2026-117949"]
title: "Firefox: use-after-free in DOM core lets attacker run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "package"]
not_affected_if: ["fixed-version"]
published_at: "2026-10-27T14:16:50+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:35:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117949", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

# Firefox: use-after-free in DOM core lets attacker run code

A use-after-free bug in the DOM Core and HTML component of Firefox was fixed in Firefox 159 and Firefox ESR 115.44 and 153.6. Sources do not say what an attacker can do with it beyond the memory corruption class.

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

## How to check

- Check the installed Firefox version in the browser's About page or with `firefox --version`
- Compare it against the fixed versions `159`, `115.44` and `153.6`, unknown for other branches

## Fix

- Update Firefox to `159` or later
- Update Firefox ESR to `115.44` or `153.6`, whichever branch is in use

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117949

## 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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