CVE-2026-8959
May 20, 2026, 2:28 p.m.
9.6
Critical
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.
Product(s) Impacted
| Vendor | Product | Versions |
|---|---|---|
| Mozilla |
|
|
Weaknesses
Common security weaknesses mapped to this vulnerability.
CWE-20
Improper Input Validation
The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.
*CPE(s)
Affected systems and software identified for this CVE.
| Type | Vendor | Product | Version | Update | Edition | Language | Software Edition | Target Software | Target Hardware | Other Information |
|---|---|---|---|---|---|---|---|---|---|---|
| a | mozilla | firefox | / | / | / | / | esr | / | / | / |
| a | mozilla | firefox | / | / | / | / | - | / | / | / |
| a | mozilla | thunderbird | / | / | / | / | esr | / | / | / |
| a | mozilla | thunderbird | / | / | / | / | / | / | / | / |
Tags
CVSS Score
CVSS Data - 3.1
- Attack Vector: NETWORK
- Attack Complexity: LOW
- Privileges Required: NONE
- Scope: CHANGED
- Confidentiality Impact: HIGH
- Integrity Impact: HIGH
- Availability Impact: HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Timeline
Published: May 19, 2026, 2:16 p.m.
Last Modified: May 20, 2026, 2:28 p.m.
Last Modified: May 20, 2026, 2:28 p.m.
Status : Analyzed
CVE is currently being analyzed by NVD staff, this process results in association of reference link tags, CVSS scores, CWE association, and CPE applicability statements.
More infoSource
*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.