Summaryinfo

A vulnerability classified as critical was found in Mozilla Firefox up to 148. Affected is an unknown function. The manipulation results in memory corruption. This vulnerability was named CVE-2026-4720. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in Mozilla Firefox up to 148. Affected is an unknown function. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Memory safety bugs present in Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

The advisory is available at bugzilla.mozilla.org. This vulnerability is traded as CVE-2026-4720 since 03/24/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 03/28/2026).

The vulnerability scanner Nessus provides a plugin with the ID 303907 (FreeBSD : Mozilla -- Multiple vulnerabilities (6d445322-2945-11f1-8461-b42e991fc52e)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 149 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (303907). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Web Browser

Vendor

• Mozilla

Name

• Firefox

Version

• 148

License

• open-source

Website

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

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