---
id: "CVE-2019-11708"
kind: "vulnerability"
aliases: ["CVE-2019-11708"]
title: "Mozilla Firefox and Thunderbird: Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability"
severity: "critical"
cvss: 10.0
epss: 0.55874
exploited: true
status: "open"
category: "package"
products: [{"name": "Mozilla Firefox and Thunderbird", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["desktop", "exploited", "firefox", "linux", "macos", "package", "thunderbird", "windows"]
not_affected_if: ["unknown"]
published_at: "2019-07-23T14:15:15+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-11708", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2019-11708", "first_seen_at": "2026-10-23T19:13:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-11708", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Mozilla Firefox and Thunderbird: Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability

Mozilla Firefox and Thunderbird contain a sandbox escape flaw that is listed as exploited in the wild. An attacker who gets a malicious page or message to run can break out of the browser sandbox and run code on the user's machine.

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

## Affected

- vendor:Mozilla Firefox and Thunderbird affected ? fixed ?

## How to check

Check the installed Firefox or Thunderbird version under Help > About; the sources do not give the affected version range.

## Fix

Update Firefox and Thunderbird to the latest release, as CISA's required action says: apply updates per vendor instructions.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2019-11708
- 2026-10-23T19:13:45+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2019-11708
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2019-11708

## From the sources

Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxed parent process opening web content chosen by a compromised child process. When combined with additional vulnerabilities this could result in executing arbitrary code on the user's computer. This vulnerability affects Firefox ESR < 60.7.2, Firefox < 67.0.4, and Thunderbird < 60.7.2.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_