External risk intelligence

Firefox AudioVideo Integer Overflow Vulnerability

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-16395

This vulnerability affects the Audio/Video component of a web browser (Firefox). Browser vulnerabilities are client-side issues requiring a user to visit a malicious site or process specific content, rather than representing an internet-facing service, gateway, or appliance that is reachable or exploitable as a standalone public network service.

Integer Overflow

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

An integer overflow vulnerability exists in the Audio/Video component of Firefox, which could allow for significant compromise of confidentiality, integrity, and availability. While patched, confirming relevance and exposure is key.

Audio/Video component flaw allows major system compromise.
Matters if we use affected browser technology.
Confirm if our systems and users are exposed.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by tricking a user into visiting a malicious website or opening a specially crafted file. This would trigger an integer overflow within the browser's Audio/Video component, potentially allowing the attacker to achieve high impact on confidentiality, integrity, and availability.

No authentication or user interaction required.
Triggered by processing media content.
High impact on confidentiality, integrity, and availability.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in the Audio/Video component could allow for critical impacts when processing specific media content. An integer overflow could lead to code execution, potentially affecting the confidentiality, integrity, and availability of the affected system.

System and user data could be impacted.
Malicious media content may trigger the overflow.
Complete system compromise is a possibility.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability affects the Audio/Video component of Firefox, which is client-side software. Ownership will likely fall to teams managing end-user computing and application deployments, such as desktop support, endpoint engineering, or application owners responsible for the browser as a managed application. The first step is to identify all systems with the affected browser version, confirm its business criticality, and then plan remediation, potentially coordinating with vendor management for the browser.

Own by endpoint or application management teams.
Verify browser deployment and reachability.
Plan phased rollout based on risk.

Supplementary metadata

CVSS vector

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Frequently asked questions

What is the Audio/Video component in Firefox?

This component is the internal engine within the Firefox web browser responsible for decoding and rendering media streams like audio tracks and video files. It acts as the bridge between raw data from the web and the multimedia output you see or hear on your screen. Because it processes complex and often untrusted data from the internet, it is a critical area for security, as flaws here can be triggered by simply navigating to a webpage containing malicious media content.

What does an integer overflow mean for CVE-2026-16395?

This vulnerability is classified as CWE-190, which occurs when a program tries to store a number larger than its allocated memory space can hold. In the context of the Audio/Video component, this mathematical error can corrupt memory structures. This corruption is significant because it potentially allows an attacker to bypass security controls or execute unauthorized commands, leading to a complete compromise of the browser's ability to protect user data and system integrity.

How is this vulnerability triggered?

The flaw is triggered when the browser's media engine encounters specially crafted data designed to force that mathematical error. Simply having the browser installed is not enough; the engine must actively process a malicious file or stream. Importantly, this does not occur through background services or standard web traffic that does not contain specific, malformed media components. It requires the software to attempt to interpret the dangerous input.

Why does Halo Surface Signal rate this as unlikely to be internet-facing?

Halo Surface Signal identifies this as a client-side vulnerability, not a server-side service. While the attack is delivered over the internet, it targets the end-user's browser application rather than an exposed server, appliance, or network gateway. Because it requires a user to engage with specific content, it does not fit the profile of a standalone public network service that is constantly reachable by automated scanning tools.

How should I respond to CVE-2026-16395?

The primary response is to ensure your Firefox browser is updated to version 153 or later, where this issue was addressed. Begin by auditing your environment to locate all managed workstations or devices running older versions of the browser. Once identified, prioritize these systems for an update rollout. Because this is client-side software, coordination with your desktop support or endpoint management teams is the most effective way to deploy the fix.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.