Sandbox Escape in Firefox Networking Component
CVE-2026-16388

9.8CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Thunderbird
Vendor
CVE Published:
21 July 2026

What is CVE-2026-16388?

A sandbox escape was identified in the networking component of Firefox, allowing unrestricted access beyond the intended execution environment. This issue could potentially enable malicious scripts to execute on users' systems, bypassing critical security measures. Mozilla addressed this vulnerability in the latest updates to ensure enhanced security for its users.

Affected Version(s)

Firefox 153

Thunderbird 153

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2043845
https://www.mozilla.org/security/advisories/mfsa2026-68/
https://www.mozilla.org/security/advisories/mfsa2026-71/

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Yaqoub Aldurayhim
.