---
id: "CVE-2026-117946"
kind: "vulnerability"
aliases: ["CVE-2026-117946"]
title: "Firefox: JavaScript engine boundary check flaw, fixed in 159"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop-browsers", "firefox", "runtime"]
not_affected_if: []
published_at: "2026-10-27T14:16:50+00:00"
first_seen_at: "2026-10-27T14:32:23+00:00"
updated_at: "2026-10-27T14:35:42+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117946", "first_seen_at": "2026-10-27T14:32:23+00:00"}]
---

# Firefox: JavaScript engine boundary check flaw, fixed in 159

The JavaScript engine in Firefox has an incorrect boundary condition check, according to the NVD entry. The sources do not say what an attacker can read or run as a result.

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

## How to check

- Check the Firefox version with `about:support` and compare it against `159`, `115.44` (ESR) or `153.6` (ESR)
- unknown

## Fix

- Update Firefox to `159` or later, or Firefox ESR to `115.44` or `153.6`

## Timeline

- 2026-10-27T14:32:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117946

## From the sources

Incorrect boundary conditions in the JavaScript Engine component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.

---

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