Process Isolation Vulnerability in Firefox and Thunderbird
CVE-2025-4083

9.1CRITICAL

Key Information:

Vendor

Mozilla
Status
Firefox
Firefox Esr
Thunderbird
Vendor
CVE Published:
29 April 2025

What is CVE-2025-4083?

A process isolation vulnerability in Firefox and Thunderbird arises from improper handling of javascript: URIs. This flaw allows content to potentially execute in the top-level document's process rather than within its intended frame, posing a risk of sandbox escape. Affected versions include Firefox versions prior to 138, Firefox ESR versions before 128.10 and 115.23, as well as Thunderbird versions prior to 138 and its ESR counterpart under 128.10. Users are advised to update to mitigate the risk.

Affected Version(s)

Firefox < 138

Firefox ESR < 128.10

Firefox ESR < 115.23

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1958350
https://www.mozilla.org/security/advisories/mfsa2025-28/
https://www.mozilla.org/security/advisories/mfsa2025-29/

CVSS V3.1

Score:
9.1
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

Nika Layzell
.
CVE-2025-4083 : Process Isolation Vulnerability in Firefox and Thunderbird