---
id: "CVE-2026-117890"
kind: "vulnerability"
aliases: ["CVE-2026-117890"]
title: "Firefox JavaScript engine: JIT miscompilation may let a web page run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop-browsers", "end-user-devices", "firefox", "runtime"]
not_affected_if: ["chromium-or-other-browsers", "no-firefox-installed"]
published_at: "2026-10-27T14:16:44+00:00"
first_seen_at: "2026-10-27T14:32:22+00:00"
updated_at: "2026-10-27T14:37:49+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117890", "first_seen_at": "2026-10-27T14:32:22+00:00"}]
---

# Firefox JavaScript engine: JIT miscompilation may let a web page run code

The JIT compiler in Firefox's JavaScript engine generated incorrect machine code in some cases. A malicious web page could use this to corrupt memory and potentially run code in the browser.

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

## How to check

- Check the Firefox version in Help > About Firefox, or run `firefox --version`
- Check whether Firefox ESR is in use, and whether its version is below `153.6`

## Fix

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

## Timeline

- 2026-10-27T14:32:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117890

## From the sources

JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.

---

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