---
id: "CVE-2026-117929"
kind: "vulnerability"
aliases: ["CVE-2026-117929"]
title: "Firefox: use-after-free in DOM core and HTML lets attackers run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "firefox-esr", "runtime"]
not_affected_if: ["already-patched-versions"]
published_at: "2026-10-27T14:16:48+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:37:09+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117929", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

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

A use-after-free bug in the Firefox DOM Core and HTML component lets memory that was already released be reused. The sources do not say what an attacker gets beyond that, so the reach and impact below are unconfirmed.

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

## How to check

- Run `firefox --version` or check Help > About Firefox and compare with the fixed versions
- Check Firefox ESR installs for `115.44` or `153.6`, or a newer build

## Fix

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

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117929

## 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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