CVE-2025-4083 Process isolation bypass using "javascript:" URI links in cross-origin frames

What is CVE-2025-4083?

CVE-2025-4083 is a critical vulnerability in Mozilla Firefox, published on 29 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.

Weakness: CWE-653

Which versions are affected by CVE-2025-4083?

It affects 2 products.

Products include Mozilla Firefox, Mozilla Thunderbird.

How do I fix CVE-2025-4083?

Upgrade to a fixed version.

Is CVE-2025-4083 being exploited?

There is no known exploitation of CVE-2025-4083 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Firefox

• CVE-2019-11708 Mozilla Firefox and Thunderbird Sandbox Escape Exploited Critical 10.0
• CVE-2010-3765 Mozilla Multiple Products Remote Code Execution Exploited Critical 9.8
• CVE-2022-26486 Mozilla Firefox Use-After-Free Exploited Critical 9.6
• CVE-2022-26485 Mozilla Firefox Use-After-Free Exploited High 8.8
• CVE-2019-11707 Mozilla Firefox and Thunderbird Type Confusion Exploited High 8.8

All Mozilla Firefox vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2025-4083, GHSA-v4qx-h7r5-6qc8, UBUNTU-CVE-2025-4083.