CVE-2026-8959

CRITICAL EPSS 33.4%
Published May 19, 20261mo ago · Modified Jun 17, 20261w ago
9.6 CVSS 3.1
Critical
Find Similar
Published May 19, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
9.6
Exploitability
2.8
Impact
6.0
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Changed
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
33.4% percentile
Exploit & Patch Status
No Known Exploit
No Patch Available

Weaknesses 3

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer Memory Safety
CWE-20 Improper Input Validation Validation
CWE-693

Affected Products 4

VendorProductVersionRange
mozillafirefox* <140.11.0
mozillafirefox* <151.0.0
mozillathunderbird* <140.11
mozillathunderbird* <151.0.0

References 5

  • bugzilla.mozilla.org https://bugzilla.mozilla.org/show_bug.cgi?id=2034754
    Permissions Required
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-46/
    Vendor Advisory
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-48/
    Vendor Advisory
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-50/
    Vendor Advisory
  • mozilla.org https://www.mozilla.org/security/advisories/mfsa2026-51/
    Vendor Advisory

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.