---
id: "CVE-2026-117899"
kind: "vulnerability"
aliases: ["CVE-2026-117899"]
title: "Firefox: use-after-free in HTTP networking can be triggered by crafted content"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop", "firefox", "managed-fleets", "runtime"]
not_affected_if: ["already-on-fixed-version"]
published_at: "2026-10-27T14:16:45+00:00"
first_seen_at: "2026-10-27T14:32:22+00:00"
updated_at: "2026-10-27T14:37:39+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-117899", "first_seen_at": "2026-10-27T14:32:22+00:00"}]
---

# Firefox: use-after-free in HTTP networking can be triggered by crafted content

A use-after-free bug in Firefox's HTTP networking component reuses memory after it has been freed. The sources do not say what an attacker gets from it, beyond that it was fixed in Firefox 159, Firefox ESR 115.44 and Firefox ESR 153.6.

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

## How to check

- Run `firefox --version` or open Help > About Firefox and compare with `159`, `115.44` or `153.6`.
- Check the installed ESR branch version on managed Firefox deployments.

## Fix

- Update Firefox to `159` or later.
- Update Firefox ESR to `115.44` or `153.6`, depending on the branch in use.

## Timeline

- 2026-10-27T14:32:22+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117899

## From the sources

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

---

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