---
id: "CVE-2026-117877"
kind: "vulnerability"
aliases: ["CVE-2026-117877"]
title: "Firefox: use-after-free in text layout lets attacker run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "other"
products: []
ecosystems: []
tags: ["browsers", "desktop", "firefox", "firefox-esr", "other"]
not_affected_if: ["already-on-fixed-version"]
published_at: "2026-10-27T14:16:43+00:00"
first_seen_at: "2026-10-27T14:32:21+00:00"
updated_at: "2026-10-27T14:39:06+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117877", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: use-after-free in text layout lets attacker run code

A use-after-free flaw in Firefox's Layout: Text and Fonts component lets memory be reused after it is freed. The sources do not say what an attacker can do beyond that, but memory corruption of this kind in a browser is commonly exploited to run code.

_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 versions.
- Check the Firefox ESR line with the same command on ESR installs.

## Fix

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

## Timeline

- 2026-10-27T14:32:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117877

## From the sources

Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.

---

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