CVE-2026-109775 in Firefox
Summary
by MITRE • 10/13/2026
Denial-of-service in the WebRTC component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.
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Analysis
by VulDB Data Team • 10/14/2026
The identified vulnerability resides within the Web Real-Time Communication (WebRTC) implementation of Mozilla Firefox, specifically affecting versions prior to Firefox 158 and Firefox Extended Support Release (ESR) 153.5. WebRTC is a critical framework that enables real-time communication features such as audio and video conferencing directly within web browsers without requiring plugins or third-party software. The flaw manifests as a denial-of-service condition, which implies that the vulnerability allows an attacker to disrupt the normal functioning of the application rather than gaining unauthorized access to data or system controls. This type of defect typically arises from improper handling of specific inputs or states within the complex media processing pipelines that WebRTC utilizes for establishing peer-to-peer connections and managing multimedia streams.
From a technical perspective, denial-of-service vulnerabilities in browser components often stem from issues such as infinite loops, memory corruption leading to crashes, or resource exhaustion during the parsing or rendering of maliciously crafted web content. In the context of WebRTC, an attacker could potentially craft a specially designed webpage that triggers this flaw when accessed by a victim using the affected Firefox version. The exploitation process likely involves sending malformed data packets or triggering specific state transitions in the media engine that cause the browser to become unresponsive or terminate unexpectedly. This behavior prevents legitimate users from accessing web-based communication services, effectively creating a localized service outage for any individual interacting with the malicious content.
The operational impact of this vulnerability is primarily centered on availability and user experience rather than confidentiality or integrity. When exploited, the immediate consequence is that the Firefox browser may freeze, crash, or consume excessive system resources such as CPU cycles or memory, rendering it unusable until restarted. For enterprise environments relying on WebRTC for internal communications, widespread exploitation could lead to significant productivity losses if multiple endpoints are compromised simultaneously through phishing campaigns or malicious websites hosted by threat actors. While this vulnerability does not directly expose sensitive data or allow remote code execution, its potential for disruption makes it a notable risk in contexts where continuous availability of communication tools is essential.
In terms of industry classification standards, this flaw aligns with CWE-400: Uncontrolled Resource Consumption and potentially CWE-20: Improper Input Validation if the root cause involves failing to properly sanitize or validate incoming media stream data before processing. From a tactical perspective within the MITRE ATT&CK framework, this vulnerability supports techniques related to Impact, specifically Denial of Service (T1499), where adversaries aim to degrade or deny service to critical assets by exhausting resources or causing system instability. The lack of authentication requirements for web-based attacks means that any user visiting a compromised site is at risk, highlighting the importance of timely patching in mitigating such threats.
Mitigation strategies focus primarily on software updates and defensive browsing practices. Users must upgrade their browsers immediately to Firefox 158 or Firefox ESR 153.5, as these versions contain the necessary code corrections that address the underlying logic errors causing the denial-of-service condition. Organizations should ensure that automated update mechanisms are enabled for all workstations running affected browser versions to minimize the window of exposure. Additionally, deploying web filtering solutions can help block access to known malicious domains or suspicious content types that might attempt to exploit this vulnerability before patches are applied. Security teams should also monitor for indicators of compromise related to unusual browser behavior or crashes associated with WebRTC activity in their network logs.