---
id: "CVE-2026-117994"
kind: "vulnerability"
aliases: ["CVE-2026-117994"]
title: "Firefox: JavaScript garbage collector use-after-free fixed in 159"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "runtime"]
not_affected_if: ["already-on-fixed-version"]
published_at: "2026-10-27T14:16:57+00:00"
first_seen_at: "2026-10-27T14:32:25+00:00"
updated_at: "2026-10-27T14:34:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117994", "first_seen_at": "2026-10-27T14:32:25+00:00"}]
---

# Firefox: JavaScript garbage collector use-after-free fixed in 159

A use-after-free bug in the JavaScript garbage collector of Firefox can corrupt memory when the engine runs crafted code. The sources do not say what an attacker can gain beyond memory corruption, and the fix ships 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

- Check the installed Firefox version in Help > About Firefox, or run `firefox --version`, and compare it with `159` and `153.6` (ESR)
- unknown

## Fix

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

## Timeline

- 2026-10-27T14:32:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117994

## From the sources

Use-after-free in the JavaScript: GC component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.

---

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