CVE-2026-92064 - Vulnerability Details

- Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component

Description

Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

Published: 2026-09-15

Score: 8.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability is caused by incorrect boundary checks in the Widget: Win32 component, allowing an attacker to escape the sandbox reserved for that component. The weakness manifests as a buffer overflow (CWE‑119) and an improper handling of input boundaries (CWE‑501), creating a path for code or data to reach outside the intended memory region.

Affected Systems

Mozilla Firefox versions prior to 156 and Firefox ESR 153.3, as well as Mozilla Thunderbird versions prior to 156 and Thunderbird ESR 153.3, are susceptible to this flaw.

Risk and Exploitability

The CVSS score of 8.8 indicates high severity, whereas the EPSS score of less than 1% and the absence of the issue from CISA’s KEV catalogue point to a low probability of exploitation at present. The likely attack vector involves an untrusted input that triggers the faulty boundary conditions within the Widget: Win32 component; however, no active exploitation has been observed.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Mozilla

Firefox

affected

Version	Status	Constraints
`153.3`	unaffected	≤ 153.*
`156`	unaffected	≤ *

Mozilla

Thunderbird

affected

Version	Status	Constraints
`153.3`	unaffected	≤ 153.*
`156`	unaffected	≤ *

Configuration 1 [-]

OR	cpe:2.3:a:mozilla:firefox::::::::
	cpe:2.3:a:mozilla:firefox::::::::
	cpe:2.3:a:mozilla:thunderbird::::::::
	cpe:2.3:a:mozilla:thunderbird::::::::

No data.

Vendor Product Confidence Versions

Mozilla

Firefox

100%

Version	Status	Scheme	Platform
`[153.3,153.*]`	unaffected	generic	—
`[156,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the update to Firefox version 156 or newer, or to the ESR 153.3 branch if using the extended support channel
Update Thunderbird to version 156 or newer
If updating immediately is impossible, disable the Widget: Win32 component or restrict the use of features that load this component

Generated by OpenCVE AI on September 21, 2026 at 21:11 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.0011.

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=2057990
https://nvd.nist.gov/vuln/detail/CVE-2026-92064
https://www.cve.org/CVERecord?id=CVE-2026-92064
https://www.mozilla.org/security/advisories/mfsa2026-90/
https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92064
https://www.mozilla.org/security/advisories/mfsa2026-93/
https://www.mozilla.org/security/advisories/mfsa2026-94/
https://www.mozilla.org/security/advisories/mfsa2026-94/#CVE-2026-92064
https://www.mozilla.org/security/advisories/mfsa2026-96/

History

Mon, 05 Oct 2026 19:15:00 +0000

Type	Values Removed	Values Added
First Time appeared		Mozilla thunderbird
CPEs		cpe:2.3:a:mozilla:firefox:::::::: cpe:2.3:a:mozilla:thunderbird::::::::
Vendors & Products		Mozilla thunderbird

Mon, 21 Sep 2026 19:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-119
Metrics	cvssV3_1 `{'score': 3.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N'}`	ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}` cvssV3_1 `{'score': 8.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H'}`

Thu, 17 Sep 2026 19:45:00 +0000

Type	Values Removed	Values Added
Weaknesses	CWE-887

Thu, 17 Sep 2026 12:15:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-501
References		https://nvd.nist.gov/vuln/detail/CVE-2026-92064 https://www.cve.org/CVERecord?id=CVE-2026-92064 https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92064 https://www.mozilla.org/security/advisories/mfsa2026-94/#CVE-2026-92064
Metrics	threat_severity `None`	cvssV3_1 `{'score': 3.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N'}` threat_severity `Low`

Wed, 16 Sep 2026 14:45:00 +0000

Type	Values Removed	Values Added
Description	Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, and Thunderbird 156.	Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
References		https://www.mozilla.org/security/advisories/mfsa2026-96/

Wed, 16 Sep 2026 04:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-887

Tue, 15 Sep 2026 20:15:00 +0000

Type	Values Removed	Values Added
Description	Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.	Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, and Thunderbird 156.
References		https://www.mozilla.org/security/advisories/mfsa2026-94/

Tue, 15 Sep 2026 14:30:00 +0000

Type	Values Removed	Values Added
First Time appeared		Mozilla Mozilla firefox
Vendors & Products		Mozilla Mozilla firefox

Tue, 15 Sep 2026 12:45:00 +0000

Type	Values Removed	Values Added
Description		Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.
Title		Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component
References		https://bugzilla.mozilla.org/show_bug.cgi?id=2057990 https://www.mozilla.org/security/advisories/mfsa2026-90/ https://www.mozilla.org/security/advisories/mfsa2026-93/

Subscriptions

Mozilla Firefox Thunderbird

MITRE

Status: PUBLISHED

Assigner: mozilla

Published: 2026-09-15T12:34:25.898Z

Updated: 2026-09-21T18:04:39.201Z

Reserved: 2026-09-15T12:34:25.394Z

Link: CVE-2026-92064

Vulnrichment

Updated: 2026-09-21T18:04:02.783Z

NVD

Status : Analyzed

Published: 2026-09-15T13:17:01.020

Modified: 2026-10-05T18:57:41.647

Link: CVE-2026-92064

Redhat

Severity : Low

Publid Date: 2026-09-15T12:34:25Z

Links: CVE-2026-92064 - Bugzilla

OpenCVE Enrichment

Updated: 2026-09-21T21:15:14Z

Weaknesses

CWE-119
Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-501
Trust Boundary Violation

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Exploitation none

Automatable no

Technical Impact total

Subscriptions

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