CVE-2026-74961 in Firefox
Summary
by MITRE • 08/18/2026
Side-channel in the Web Audio component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.
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Analysis
by VulDB Data Team • 08/18/2026
The identified side-channel vulnerability within Mozilla's Web Audio API presents a sophisticated risk to user privacy, specifically targeting audio processing operations that are susceptible to timing-based information leakage. Side-channel attacks exploit indirect information gained from the physical implementation of a system rather than weaknesses in the design itself. In this context, the flaw likely stems from inconsistent execution times or memory access patterns during audio buffer manipulation, sample rate conversion, or effect chain processing within the browser engine. Attackers can leverage these minute timing discrepancies to infer sensitive data about the user's environment, such as specific hardware configurations, active applications running in other tabs, or even keystrokes if microphone input is involved and processed through vulnerable pathways. This type of vulnerability falls under CWE-358, which classifies improper exploitation of a side-channel for information disclosure, highlighting how non-functional attributes like execution time can compromise confidentiality.
The operational impact of this flaw extends beyond simple data leakage to potential cross-site tracking and fingerprinting capabilities that are difficult for users to detect or mitigate through standard privacy settings. By analyzing the precise timing of audio context creation, node connections, or buffer rendering operations, a malicious website could construct a unique profile of the victim's device characteristics with high precision. This undermines the effectiveness of browser-based anti-fingerprinting measures and allows adversaries to correlate user activity across different sessions and domains without relying on traditional cookies or local storage mechanisms. The vulnerability is particularly concerning because Web Audio API interactions are often triggered by legitimate user actions, making it challenging for automated security tools to distinguish between benign audio processing and malicious probing attempts in real-time.
To address this issue, Mozilla released fixes in Firefox version 154 and the extended support release version 153.1, which likely involve introducing constant-time algorithms for critical audio operations or adding randomization delays to obscure timing differences that could be exploited by an attacker. These mitigations aim to ensure that execution time remains consistent regardless of the input data or internal state variations that might reveal sensitive information. Users are strongly advised to update their browsers immediately to patch this vulnerability, as older versions remain exposed to sophisticated side-channel attacks. Additionally, developers utilizing the Web Audio API should review their implementations for any custom audio processing logic that might inadvertently expose timing leaks and consider adopting defensive programming practices such as constant-time comparisons where applicable. From a broader security perspective, this incident underscores the importance of adhering to secure coding guidelines outlined in standards like OWASP Secure Coding Practices, particularly those related to preventing information leakage through side channels. Security researchers and penetration testers should also be aware that modern browsers are increasingly targeted by advanced persistent threats leveraging such subtle implementation flaws, necessitating continuous monitoring and rapid patch deployment cycles as demonstrated by the swift resolution provided in these recent Firefox releases.