CVE-2026-8959 Details
Description
Sandbox escape due to incorrect boundary conditions in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
A sandbox escape vulnerability has been identified in the Widget: Win32 component of Mozilla Firefox. This issue arises from incorrect boundary conditions, allowing for unauthorized access or actions within the application's sandbox environment. The vulnerability affects Firefox versions prior to 151 and Firefox ESR versions prior to 140.11.
Users can upgrade to Firefox 151 or Firefox ESR 140.11 to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 19, 2026References to Advisories, Solutions, and Tools
By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.
| URL | Source(s) | Tag(s) |
|---|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=2034754 | [email protected] | Permissions Required |
| https://www.mozilla.org/security/advisories/mfsa2026-46/ | [email protected] | Vendor Advisory |
| https://www.mozilla.org/security/advisories/mfsa2026-48/ | [email protected] | Vendor Advisory |
| https://www.mozilla.org/security/advisories/mfsa2026-50/ | [email protected] | Vendor Advisory |
| https://www.mozilla.org/security/advisories/mfsa2026-51/ | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-119 | Improper Restriction of Operations within the Bounds of a Memory Buffer | CISA-ADP |
| CWE-20 | Improper Input Validation | CISA-ADP |
| CWE-693 | Protection Mechanism Failure | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| mozilla firefox | < 140.11.0 < 151.0.0 |
CPE
Remediation
| |
| mozilla thunderbird | < 140.11 < 151.0.0 |
CPE
Remediation
| |
Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 20, 2026 | Initial Analysis | [email protected] |
| May 19, 2026 | CVE Modified | [email protected] |
| May 19, 2026 | CVE Modified | CISA-ADP |
| May 19, 2026 | New CVE Received | [email protected] |