CVE-2026-109705

Summary

This vulnerability is a use-after-free flaw in Firefox's networking component that allows attackers to escape the browser sandbox and potentially execute arbitrary code with high privileges. The issue occurs due to incorrect boundary conditions in site isolation, making it particularly dangerous for web-based attacks.

Exploitability

Exploitation requires a user visiting a malicious website with specific JavaScript payloads, but is relatively straightforward once the user is on the page since it leverages well-understood use-after-free patterns.

Blast radius

If exploited, this vulnerability could allow attackers to escape browser sandboxing and execute arbitrary code on the victim's system with full user privileges, potentially leading to complete system compromise.

Detection

No reliable host or network indicator is derivable from the published description.

Prioritized remediation

Upgrade to Firefox 158 or Thunderbird 158 immediately, as these versions contain the fix for this critical sandbox escape vulnerability.

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.