---
id: "CVE-2026-117883"
kind: "vulnerability"
aliases: ["CVE-2026-117883"]
title: "Firefox: use-after-free in HTML parser can crash or run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "runtime"]
not_affected_if: ["already-updated-browser"]
published_at: "2026-10-27T14:16:43+00:00"
first_seen_at: "2026-10-27T14:32:21+00:00"
updated_at: "2026-10-27T14:37:57+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117883", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: use-after-free in HTML parser can crash or run code

A use-after-free bug in the DOM HTML Parser component of Firefox lets memory be reused after it is freed. Sources do not say what an attacker can achieve with it beyond the general risk of memory corruption.

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

## How to check

- Check the Firefox version with `about:support` or the Help menu and compare it to the fixed releases
- Check ESR installs against `115.44` and `153.6`

## Fix

- Update Firefox to `159` or later
- Update Firefox ESR 115 to `115.44` or later
- Update Firefox ESR 153 to `153.6` or later

## Timeline

- 2026-10-27T14:32:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117883

## From the sources

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

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