Is CVE-2026-92071 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-92071 being exploited in the wild.

How severe is CVE-2026-92071?

Critical severity, with a CVSS score of 9.6, published 15 September 2026.

Which products and versions are affected?

Mozilla Firefox before 156; Mozilla Firefox ESR before 153.3; Mozilla Thunderbird before 153.3.

Is there a fix for CVE-2026-92071?

A patch was published on 2026-09-15: Fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, Thunderbird 153.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-92071 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-92071?

Check whether you run Mozilla Firefox, Mozilla Firefox ESR or Mozilla Thunderbird 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.

CVE-2026-92071: Mozilla Firefox sandbox escape in Widget: Win32 component

CVE-2026-92071 · Severity: critical · CVSS 9.6 · Published 2026-09-15

Firefox's Win32 widget component contains a flaw that allows attackers to escape the browser's security sandbox through incorrect boundary condition checks. A successful exploit could allow malicious web content to break out of the sandbox and access the underlying operating system with the privileges of the user running Firefox, potentially leading to full system compromise.

Technologies: Mozilla Firefox, Mozilla Firefox ESR, Mozilla Thunderbird. Vendors: Mozilla.

Quick answers

Is CVE-2026-92071 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-92071 being exploited in the wild.
How severe is CVE-2026-92071?: Critical severity, with a CVSS score of 9.6, published 15 September 2026.
Which products and versions are affected?: Mozilla Firefox before 156; Mozilla Firefox ESR before 153.3; Mozilla Thunderbird before 153.3.
Is there a fix for CVE-2026-92071?: A patch was published on 2026-09-15: Fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, Thunderbird 153.3 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-92071 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-92071?: Check whether you run Mozilla Firefox, Mozilla Firefox ESR or Mozilla Thunderbird 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

This vulnerability is a sandbox escape caused by incorrect boundary condition validation in the Widget: Win32 component. The flaw allows an attacker to bypass browser sandbox restrictions through crafted input that exploits the boundary condition check. Attack requires network connectivity and user interaction (opening a malicious web page or email), but no authentication is needed. A successful exploit enables arbitrary code execution outside the sandbox with the privileges of the user's browser process. The vulnerability is fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Affected products

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

Timeline

2026-09-15: disclosed: CVE-2026-92071 published
2026-09-15: patched: Fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, Thunderbird 153.3

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.