Several vulnerabilities in Mozilla Firefox could allow arbitrary code execution

Several vulnerabilities have been discovered in Mozilla Firefox, the most serious of which could allow arbitrary code execution. Mozilla Firefox is a web browser used to access the Internet. Successful exploitation of the most severe of these vulnerabilities could allow arbitrary code execution. Depending on the privileges associated with the user, an attacker could then install programs; view, modify or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system might be less affected than those who operate with administrative user rights.

There are currently no reports of these vulnerabilities being exploited in the wild.

Several vulnerabilities have been discovered in Mozilla Firefox, the most serious of which could allow arbitrary code execution. The details of these vulnerabilities are as follows:

Tactical: Initial access (TA0001):

Technical: Compromise while driving (T1189)

• Heap buffer overflow in audio/video. (CVE-2026-3845)
• Bypassing the same-origin policy in the CSS Parsing and Computation component. (CVE-2026-3846)
• Memory security bugs fixed in Firefox 148.0.2. (CVE-2026-3847)

Successful exploitation of the most severe of these vulnerabilities could allow arbitrary code execution. Depending on the privileges associated with the user, an attacker could then install programs; view, modify or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system might be less affected than those who operate with administrative user rights.

We recommend that the following actions be taken:

• Apply appropriate updates provided by Mozilla to vulnerable systems immediately after appropriate testing. (M1051: Update software)
• Backup 7.1: Establish and maintain a vulnerability management process: Establish and maintain a documented vulnerability management process for company assets. Review and update documentation annually or when significant changes within the business occur that could impact this protection.
• Backup 7.4: Perform automated application patch management: Perform application updates on enterprise assets with automated patch management on a monthly or more frequent basis.
• Backup 7.7: Fix detected vulnerabilities: Remediate detected vulnerabilities in software through processes and tools on a monthly or more frequent basis, depending on the remediation process.
• Backup 9.1: Make sure you only use fully supported browsers and email clients: Ensure that only fully supported browsers and email clients are allowed to run in the enterprise, using only the latest version of vendor-provided browsers and email clients.
• Apply the principle of least privilege to all systems and services. Run all software as an unprivileged user (without administrative privileges) to lessen the effects of a successful attack. (M1026: Management of privileged accounts)
• Backup 4.7: Manage default accounts on company assets and software: Manage default accounts on company assets and software, such as root, administrator, and other preconfigured vendor accounts. Example implementations may include: disabling default accounts or rendering them unusable.
• Backup 5.4: Restrict administrator privileges to dedicated administrator accounts: Limit administrator privileges to dedicated administrator accounts on company assets. Perform general computing activities, such as browsing the Internet, email, and using the Productivity Suite, from the user’s primary, non-privileged account.
• Use features to detect and block conditions that could lead to or indicate the occurrence of a software exploit. (M1050: Exploit Protection)
• Backup 10.5: Enable anti-exploitation features: Enable anti-exploitation features on company assets and software where possible, like Microsoft? Data Execution Prevention (DEP), Windows? Defender Exploit Guard (WDEG) or Apple? System Integrity Protection (SIP) and Gatekeeper™.
• Restrict use of certain websites, block downloads/attachments, block JavaScript, restrict browser extensions, etc. (M1021: Restrict web content)
• Backup 9.2: Use DNS filtering services: Use DNS filtering services on all company assets to block access to known malicious domains.
• Backup 9.3: Maintain and apply network-based URL filters: Apply and update network-based URL filters to prevent a business asset from connecting to potentially malicious or untrusted websites. Example implementations include category-based filtering, reputation-based filtering, or the use of blocklists. Apply filters for all company assets.
• Backup 9.6: Block unnecessary file types: Block unnecessary file types that attempt to access the company’s email gateway.
• Restrict code execution to a virtual environment on or in transit to an endpoint system. (M1048: Application isolation and sandboxing)
• Backup 4.1: Establish and maintain a secure configuration process: Establish and maintain a secure configuration process for business assets (end user devices, including wearable and mobile, non-IT/IoT devices and servers) and software (operating systems and applications). Review and update documentation annually or when significant changes within the business occur that could impact this protection.
• Backup 16.8: Separate production and non-production systems: Maintain separate environments for production and non-production systems.
• Inform and educate users about the threats posed by hyperlinks contained in emails or attachments, especially from untrusted sources. Remind users not to visit untrustworthy websites or follow links provided by unknown or untrustworthy sources. (M1017: User training)
• Backup 14.1: Establish and maintain a security awareness program: Establish and maintain a security awareness program. The goal of a security awareness program is to educate company personnel on how to interact with company assets and data securely. Organize training upon hiring and, at a minimum, once a year. Review and update the content annually or when significant changes within the business occur that could impact this protection.
• Backup 14.2: Train staff members to recognize social engineering attacks: Train your staff to recognize social engineering attacks, such as phishing, fake text, and tailgating.