CRITICAL

CVE-2026-100819

CVSS v3

9.6

CRITICAL

EPSS Score

—

exploit probability

CISA KEV

known exploited

Exploitation

—

SSVC status

Description

Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
Published: 2026-09-29
Last Modified: 2026-09-29

Frequently asked questions

What is CVE-2026-100819?

Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

Is CVE-2026-100819 actively exploited?

Active exploitation of CVE-2026-100819 has not been confirmed.

What is the CVSS score for CVE-2026-100819?

CVE-2026-100819 has a CVSS v3 base score of 9.6 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

Is CVE-2026-100819 affecting your environment?

Use isMalicious to check if any of your IPs or domains are associated with this vulnerability's IOCs.

Check an IP Search CVEs SIEM & TIP integrations

No credit card required · 500 free checks/month · Free API key

Other 2026 vulnerabilities worth triaging

Ranked by exploit probability (EPSS).

Back to CVE Database