CVE-2026-84126

Incorrect boundary conditions in the Layout: Grid component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.

  • Published Sep 1, 2026
  • CVSS 4.3 medium
  • 0.3% chance of exploitation in the next 30 days (EPSS)
  • A fix is available

Affected software

CVE-2026-84126 at the National Vulnerability Database