---
id: "CVE-2026-117872"
kind: "vulnerability"
aliases: ["CVE-2026-117872"]
title: "Firefox: use-after-free in JavaScript standard library can be exploited"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "runtime"]
not_affected_if: ["up-to-date-firefox"]
published_at: "2026-10-27T14:16:41+00:00"
first_seen_at: "2026-10-27T14:32:21+00:00"
updated_at: "2026-10-27T14:39:15+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117872", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: use-after-free in JavaScript standard library can be exploited

A use-after-free bug in the JavaScript Standard Library component of Firefox frees memory that is still referenced, which can corrupt memory. The sources do not say what an attacker can achieve beyond that, such as code execution.

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

## How to check

- Run `firefox --version` (or check Help > About Firefox) and compare against the fixed releases listed below
- unknown for ESR installs beyond the listed versions

## 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-2026-117872

## From the sources

Use-after-free in the JavaScript: Standard Library component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_