Summaryinfo

A vulnerability, which was classified as critical, was found in Mozilla Firefox up to 148. Affected by this issue is some unknown functionality. Such manipulation leads to memory corruption. This vulnerability is referenced as CVE-2026-4729. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 148 and classified as critical. Affected by this issue is some unknown functionality. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Memory safety bugs present in 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 and Thunderbird < 149.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability is handled as CVE-2026-4729 since 03/24/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 03/28/2026).

The vulnerability scanner Nessus provides a plugin with the ID 304138 (Linux Distros Unpatched Vulnerability : CVE-2026-4729), 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 (304138). If you want to get best quality of vulnerability data, you may have to visit VulDB.

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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