---
id: "CVE-2026-117990"
kind: "vulnerability"
aliases: ["CVE-2026-117990"]
title: "Firefox WebRender: boundary check flaw allows sandbox escape"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "firefox-esr", "other"]
not_affected_if: ["already-updated"]
published_at: "2026-10-27T14:16:56+00:00"
first_seen_at: "2026-10-27T14:32:24+00:00"
updated_at: "2026-10-27T14:34:59+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117990", "first_seen_at": "2026-10-27T14:32:24+00:00"}]
---

# Firefox WebRender: boundary check flaw allows sandbox escape

Firefox's WebRender graphics component has incorrect boundary conditions that let a crafted page escape the browser sandbox. The fix shipped in Firefox 159 and Firefox ESR 153.6.

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

## How to check

- Run `firefox --version` (or check About Firefox) and compare against `159` or ESR `153.6`
- Check the managed fleet inventory for Firefox ESR builds older than `153.6`

## Fix

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

## Timeline

- 2026-10-27T14:32:24+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117990

## From the sources

Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.

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