CVE-2026-92043 in Firefox
Summary
by MITRE • 09/15/2026
Privilege escalation due to incorrect boundary conditions in the Audio/Video component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.
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Analysis
by VulDB Data Team • 09/15/2026
The identified security flaw resides within the audio and video processing subsystem of Mozilla Firefox, specifically involving a failure in proper boundary condition checks during memory management operations. In complex multimedia handling scenarios, such as decoding or encoding high-resolution streams with specific frame rates or codec configurations, the software failed to correctly validate input parameters against allocated buffer limits. This logical error allows an attacker who can craft and deliver malicious media content to trigger an out-of-bounds write operation within the application's memory space. The vulnerability is classified under CWE-787: Out-of-Bounds Write, which represents a critical category of memory corruption vulnerabilities where data is written beyond the intended boundaries of a buffer, potentially overwriting adjacent memory structures and leading to arbitrary code execution or system compromise.
From an operational perspective, this privilege escalation vector poses significant risks because it can be exploited through standard web browsing activities without requiring user interaction beyond visiting a maliciously crafted webpage containing the exploit payload. Attackers could embed specially formatted audio or video files within HTML5 media elements that trigger the boundary condition failure during playback. Successful exploitation allows for arbitrary code execution with the privileges of the current user, which may lead to full system compromise if additional post-exploitation techniques are employed. The impact extends beyond simple data theft, as it enables attackers to install malware, establish persistent backdoors, or pivot within a network environment depending on the victim's access levels and security posture.
The technical root cause stems from insufficient validation of array indices or buffer sizes before performing write operations in the media decoder pipeline. When processing certain edge cases involving specific container formats or codec-specific metadata, the application miscalculates the required memory allocation or fails to check if subsequent writes exceed the allocated region. This type of defect is often difficult to detect through static analysis alone and typically requires dynamic testing methods such as fuzzing with targeted media files that exercise these boundary conditions. The vulnerability aligns with MITRE ATT&CK technique T1203: Exploitation for Client Execution, where adversaries leverage software vulnerabilities in client applications to execute malicious code on the target system without direct user consent beyond initial page load or media interaction.
Mitigation strategies primarily involve applying the vendor-provided patches that address these boundary checks and improve input validation logic within the audio video component. Users should ensure their browsers are updated to Firefox version 156 or later, including the Extended Support Release variant at version 153.3, which contain the necessary code corrections. In environments where immediate patching is not feasible, network-level controls such as web content filtering can help block access to domains hosting malicious media payloads. Additionally, enabling strict Content Security Policy headers and disabling unnecessary plugins or extensions that interact with multimedia processing can reduce the attack surface. Regular security awareness training for users regarding suspicious links and untrusted media sources remains a critical complementary defense measure against social engineering tactics often used in conjunction with such technical exploits.