---
id: "CVE-2026-117880"
kind: "vulnerability"
aliases: ["CVE-2026-117880"]
title: "Firefox: use-after-free in XML component may let attackers run code"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["desktop-browsers", "firefox", "runtime"]
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-2026-117880", "first_seen_at": "2026-10-27T14:32:21+00:00"}]
---

# Firefox: use-after-free in XML component may let attackers run code

A use-after-free bug in the XML component of Firefox was fixed in Firefox 159 and Firefox ESR 115.44 and 153.6. The sources do not say what an attacker gains beyond the memory corruption that a use-after-free implies.

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

## How to check

- Check the installed Firefox version in the browser's About page or with `firefox --version`, and compare it against the fixed releases.
- Check the ESR version in use, which should be `115.44` or later on the 115 branch or `153.6` or later on the 153 branch.

## Fix

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

## Timeline

- 2026-10-27T14:32:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-117880

## From the sources

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

---

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