# CVE-2026-92067: Mozilla Firefox use-after-free in Widget: Gtk component

Source: https://junglewise.ai/threats/cve-2026-92067-mozilla-firefox-use-after-free-in-widget-gtk-component  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-92067 · Severity: high · CVSS 8.8 · Published 2026-09-15

Firefox and Thunderbird contain a use-after-free memory safety vulnerability in the GTK widget library integration. An attacker could exploit this flaw to crash the browser or email client, or potentially execute arbitrary code if the vulnerability is triggered during normal use of the application.

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

## Quick answers

**Is CVE-2026-92067 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-92067 being exploited in the wild.

**How severe is CVE-2026-92067?** High severity, with a CVSS score of 8.8, published 15 September 2026.

**Which products and versions are affected?** Mozilla Firefox before 156; Mozilla Firefox ESR before 153.3; Mozilla Thunderbird before 156; Mozilla Thunderbird ESR before 153.3.

**Is there a fix for CVE-2026-92067?** A patch was published on 2026-09-15: Fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird ESR 153.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-92067 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-92067?** Check whether you run Mozilla Firefox, Mozilla Firefox ESR, Mozilla Thunderbird or one of the others listed at an affected version. 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.

## Technical details

A use-after-free vulnerability exists in the Widget: Gtk component affecting Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR. This memory corruption flaw occurs when the application references memory that has already been freed, potentially allowing an attacker to corrupt application state or achieve code execution. The vulnerability affects Firefox versions prior to 156, Firefox ESR prior to 153.3, Thunderbird prior to 156, and Thunderbird ESR prior to 153.3. The attack likely requires user interaction (e.g., loading malicious content), and patches are available in the fixed versions.

## Affected products

- Mozilla Firefox before 156
- Mozilla Firefox ESR before 153.3
- Mozilla Thunderbird before 156
- Mozilla Thunderbird ESR before 153.3

## Timeline

- 2026-09-15: disclosed: CVE-2026-92067 publicly disclosed
- 2026-09-15: patched: Fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird ESR 153.3

## References

- [https://bugzilla.mozilla.org/show_bug.cgi?id=2058664](https://bugzilla.mozilla.org/show_bug.cgi?id=2058664)
- [https://www.mozilla.org/security/advisories/mfsa2026-90/](https://www.mozilla.org/security/advisories/mfsa2026-90/)

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