---
id: "CVE-2026-117951"
kind: "vulnerability"
aliases: ["CVE-2026-117951"]
title: "Firefox: use-after-free in DOM core and HTML lets code run"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop-browsers", "firefox", "managed-fleets", "runtime"]
not_affected_if: ["no-firefox-installed"]
published_at: "2026-10-27T14:16:51+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:35:38+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117951", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

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

A use-after-free bug in the DOM Core and HTML component of Firefox can corrupt memory when a page triggers it. The sources do not say what an attacker gets beyond memory corruption, so the impact is unconfirmed.

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

## How to check

- Open `about:support` in Firefox and read the version; unknown whether the sources list affected versions beyond the fixed ones.
- Check the installed ESR branch version against the fixed releases listed in the fix field.

## Fix

- Update Firefox to `159` or later on the current channel.
- Update Firefox ESR to `115.44` on the 115 branch or `153.6` on the 153 branch.

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117951

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