CVE-2026-92048 - 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: 9 Critical

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability results from incorrect boundary checks in the Widget: Win32 component, which can enable a carefully crafted widget or code to escape the sandbox that normally isolates this component. The flaw is classified as a boundary‑violation issue (CWE‑501). As a result, code that operates only within the restricted widget context could potentially run with the privileges granted to the component, thereby reducing the effectiveness of the sandbox protection.

Affected Systems

The issue affects Mozilla Firefox versions earlier than 156 and earlier Earth‑Release versions (ESR) prior to 153.3, as well as Mozilla Thunderbird versions earlier than 156 and ESR versions prior to 153.3.

Risk and Exploitability

The CVSS score of 9.0 indicates a high severity assessment. The EPSS score of less than 1% suggests that the likelihood of exploitation is currently very low. The vulnerability is not listed in the CISA KEV catalog. No publicly released exploit variants are known, and the lack of listed exploitation activity further implies that active exploitation is not documented at this time. The potential impact is limited to environments that allow loading of widgets, and remediation should be prioritized if such usage is present.

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
`[153.3,154.0.0)`	unaffected	generic	—
`[156,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade Mozilla Firefox to version 156 or later, or to the ESR 153.3 release line or later.
Upgrade Mozilla Thunderbird to version 156 or later, or to the ESR 153.3 release line or later.
If an update cannot be performed immediately, configure the application to block the loading of widgets or disable the Widget: Win32 component to reduce the attack surface.

Generated by OpenCVE AI on September 21, 2026 at 19:42 UTC.

Tracking

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Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00295.

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=2061235
https://nvd.nist.gov/vuln/detail/CVE-2026-92048
https://www.cve.org/CVERecord?id=CVE-2026-92048
https://www.mozilla.org/security/advisories/mfsa2026-90/
https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92048
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-2026-92048
https://www.mozilla.org/security/advisories/mfsa2026-96/

History

Mon, 05 Oct 2026 19:00:00 +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

Tue, 22 Sep 2026 16:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Mon, 21 Sep 2026 18:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-119
Metrics	cvssV3_1 `{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}`	cvssV3_1 `{'score': 9.0, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H'}`

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

Type	Values Removed	Values Added
Weaknesses	CWE-119

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

Type	Values Removed	Values Added
Weaknesses		CWE-501
References		https://nvd.nist.gov/vuln/detail/CVE-2026-92048 https://www.cve.org/CVERecord?id=CVE-2026-92048 https://www.mozilla.org/security/advisories/mfsa2026-90/#CVE-2026-92048 https://www.mozilla.org/security/advisories/mfsa2026-94/#CVE-2026-92048
Metrics	threat_severity `None`	cvssV3_1 `{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}` threat_severity `Moderate`

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 06:00:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-119

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 14:45:00 +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=2061235 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: 2026-09-15T12:34:09.407Z

Updated: 2026-09-21T17:37:28.075Z

Reserved: 2026-09-15T12:34:08.910Z

Link: CVE-2026-92048

Vulnrichment

Updated: 2026-09-21T17:37:10.810Z

NVD

Status : Analyzed

Published: 2026-09-15T13:16:56.493

Modified: 2026-10-05T18:44:32.257

Link: CVE-2026-92048

Redhat

Severity : Moderate

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

Links: CVE-2026-92048 - Bugzilla

OpenCVE Enrichment

Updated: 2026-09-21T19:45:17Z

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 Network

Attack Complexity Low

Privileges Required Low

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction Required

Exploitation none

Automatable no

Technical Impact total

Subscriptions

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