---
id: "CVE-2026-117931"
kind: "vulnerability"
aliases: ["CVE-2026-117931"]
title: "Firefox: use-after-free in DOM Events lets a page run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browser", "desktop", "firefox", "runtime"]
not_affected_if: ["already-on-fixed-version"]
published_at: "2026-10-27T14:16:48+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:37:06+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117931", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

# Firefox: use-after-free in DOM Events lets a page run code

A use-after-free bug in Firefox's DOM Events component lets memory be reused after it is freed. Sources do not say what an attacker can get from it, beyond that it was fixed in Firefox 159 and ESR 115.44 and 153.6.

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

## How to check

- Check the Firefox version in the About Firefox page or with `firefox --version`
- Look for ESR installs at 115.x or 153.x in the package manager

## Fix

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

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117931

## From the sources

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

---

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