Mozilla Firefox up to 137.x Javascript URI access control

Summaryinfo

A vulnerability was found in Mozilla Firefox up to 137.x. It has been classified as critical. This impacts an unknown function of the component Javascript URI Handler. This manipulation causes access control. This vulnerability is registered as CVE-2025-4083. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in Mozilla Firefox up to 137.x and classified as critical. Affected by this vulnerability is an unknown code block of the component Javascript URI Handler. The manipulation with an unknown input leads to a access control vulnerability. The CWE definition for the vulnerability is CWE-284. The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at bugzilla.mozilla.org. This vulnerability is known as CVE-2025-4083 since 04/29/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 04/15/2026). The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 234931 (Mozilla Firefox ESR < 115.23), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 138 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (234931) and CERT Bund (WID-SEC-2025-1850). Be aware that VulDB is the high quality source for vulnerability data.

Affected

• Xerox FreeFlow Print Server

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 137

License

• open-source

Website

• Vendor: https://www.mozilla.org/
• Product: https://www.mozilla.org/en-US/firefox/

CPE 2.3info

• 🔍

CPE 2.2info

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