# CVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerability

Source: https://junglewise.ai/threats/cve-2019-11707-mozilla-firefox-and-thunderbird-type-confusion-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2022-05-23. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2019-11707 · Severity: critical · CVSS 8.8 · Exploited in the wild · Published 2022-05-23

A type confusion vulnerability exists in Mozilla Firefox and Thunderbird when manipulating JavaScript objects via Array.pop. This flaw can result in an exploitable crash and potential arbitrary code execution.

Technologies: [Mozilla Firefox](https://junglewise.ai/threats/technologies/firefox), [Mozilla Thunderbird](https://junglewise.ai/threats/technologies/thunderbird). Vendors: [Mozilla](https://junglewise.ai/threats/vendors/mozilla).

## Quick answers

**Is CVE-2019-11707 exploited in the wild?** Yes. CVE-2019-11707 is known to be exploited in the wild, first recorded on 23 May 2022. Treat it as urgent.

**How severe is CVE-2019-11707?** Critical severity, with a CVSS score of 8.8, published 23 May 2022.

**Which products and versions are affected?** Mozilla Firefox ESR < 60.7.1; Mozilla Firefox < 67.0.3; Mozilla Thunderbird < 60.7.2.

**Is there a fix for CVE-2019-11707?** A patch was published on 2019-06-18: Mozilla released security advisories MFSA2019-18 and MFSA2019-20 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2019-11707 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2019-11707?** Check whether you run Mozilla Firefox or Mozilla Thunderbird. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Mozilla Firefox ESR < 60.7.1
- Mozilla Firefox < 67.0.3
- Mozilla Thunderbird < 60.7.2

## Timeline

- 2019-07-23: disclosed: NVD Published Date
- 2022-05-23: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2019-06-18: patched: Mozilla released security advisories MFSA2019-18 and MFSA2019-20
- 2019-06-18: exploited: Reported as being exploited in targeted attacks in the wild at time of disclosure

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