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Findings

CVE-2026-8959

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

Published May 19, 2026 · updated Oct 14, 2026 · mozilla firefox

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.

Timeline

Detection, updates, and resolution for this record.

  1. May 19, 2026 · NIST NVD

    Detected

    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.

  2. Oct 14, 2026 · NIST NVD

    Updated

    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.

Affected

  • cpe mozilla/firefoxversion unspecified
  • cpe mozilla/thunderbirdversion unspecified

Sources

  • CVE.orgCVE-2026-8959

    Official CVE identifier

    cve.org
  • FIRST EPSSCVE-2026-8959

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDCVE-2026-8959

    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.

    nvd.nist.gov

References