---
id: "CVE-2026-117861"
kind: "vulnerability"
aliases: ["CVE-2026-117861"]
title: "Firefox: DOM navigation flaw lets web content escape the sandbox"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "firefox-esr", "runtime"]
not_affected_if: ["other-browser-only"]
published_at: "2026-10-27T14:16:40+00:00"
first_seen_at: "2026-10-27T14:32:21+00:00"
updated_at: "2026-10-27T14:39:23+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117861", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: DOM navigation flaw lets web content escape the sandbox

A flaw in the DOM Navigation component of Firefox allows a sandbox escape. The sources do not say what an attacker can reach after escaping.

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

## How to check

- Check the installed Firefox version (Help > About Firefox, or `firefox --version`) and compare it with the fixed releases.
- Check whether Firefox ESR is in use and confirm its version against the fixed ESR release.

## Fix

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

## Timeline

- 2026-10-27T14:32:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117861

## Documents

- [discussion] @TheHackersNews: Mozilla released Firefox 159 and security advisories for ESR 153.6 and 115.44.

 https://x.com/TheHackersNews/status/2115099732444119324

## From the sources

Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.

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