---
id: "CVE-2026-124917"
page: "https://infrastack.ai/live/CVE-2026-124917"
kind: "vulnerability"
aliases: ["CVE-2026-124917"]
title: "Firefox: use-after-free in GTK widget lets attackers escape the sandbox"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["firefox", "firefox-esr", "gtk", "linux", "runtime"]
not_affected_if: ["already-updated", "non-gtk-platform"]
published_at: "2026-11-10T14:17:25+00:00"
first_seen_at: "2026-11-10T14:22:17+00:00"
updated_at: "2026-11-10T14:24:33+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124917", "first_seen_at": "2026-11-10T14:22:17+00:00"}]
exploit_sources: []
---

# Firefox: use-after-free in GTK widget lets attackers escape the sandbox

Link for people: https://infrastack.ai/live/CVE-2026-124917 (this .md is for agents)

A use-after-free bug in Firefox's GTK widget component allows a sandbox escape. An attacker who can get content running in the browser could use it to break out of the browser's sandbox.

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

## How to check

- Check the installed Firefox version in the About Firefox dialog or with `firefox --version`, and compare it with the fixed versions below.
- Check whether Firefox ESR is in use and its version.

## Fix

- Firefox: move to `160` or later.
- Firefox ESR: move to `153.7` or later.

## Timeline

- 2026-11-10T14:22:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124917

## From the sources

Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_