---
id: "CVE-2026-117940"
kind: "vulnerability"
aliases: ["CVE-2026-117940"]
title: "Firefox: use-after-free in DOM Core and HTML component"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["browser", "desktop", "firefox", "other"]
not_affected_if: ["firefox-159-or-later", "firefox-esr-153.6-or-later"]
published_at: "2026-10-27T14:16:49+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:36:58+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117940", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

# Firefox: use-after-free in DOM Core and HTML component

A use-after-free bug in the DOM Core and HTML component of Firefox lets a web page corrupt browser memory. The sources do not say what an attacker can get beyond that, such as code execution.

_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` or ESR `153.6`
- unknown for other checks, the sources do not say

## Fix

- Update Firefox to `159` or Firefox ESR to `153.6`
- unknown for other fixes, the sources do not say

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117940

## From the sources

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

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_