CVE-2026-100795 in Firefox
Summary
by MITRE • 09/29/2026
Denial-of-service in the Networking component. This vulnerability was fixed in Firefox 157.
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Analysis
by VulDB Data Team • 09/29/2026
The identified vulnerability resides within the networking subsystem of Mozilla Firefox, specifically affecting versions prior to release 157. As a denial-of-service flaw, this issue does not compromise the confidentiality or integrity of user data but rather targets the availability and stability of the application itself. The root cause typically involves improper handling of specific network requests or malformed packets that trigger an unhandled exception, infinite loop, or excessive resource consumption within the browser's networking stack. When a victim is directed to a maliciously crafted webpage or interacts with a specially designed server response, the vulnerability can be exploited to crash the Firefox process or render it completely unresponsive. This type of exploitation relies on the attacker controlling the input data that flows through the network layer, often by hosting a web page that triggers specific JavaScript APIs or HTTP/2 frame sequences that expose weaknesses in memory management or state machine logic within the networking component.
From an operational perspective, the impact of this vulnerability is primarily disruptive to the end-user experience rather than posing a direct security risk such as remote code execution. A successful exploit results in the termination of the browser tab or the entire application process, forcing the user to restart Firefox and potentially losing unsaved work or session data associated with open tabs. In enterprise environments where browsers are used for critical business applications, repeated denial-of-service events can lead to significant productivity losses and increased support overhead. Furthermore, if the vulnerability allows for rapid resource exhaustion without crashing the entire browser immediately, it could be leveraged in conjunction with other attacks to degrade system performance or facilitate more complex exploitation scenarios that require a stable but stressed environment. The lack of robust error handling means that even minor anomalies in network data can escalate into full service interruptions, highlighting a gap in defensive programming practices within the networking module's input validation routines.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) categories such as CWE-400: Uncontrolled Resource Consumption and CWE-787: Out-of-bounds Write if memory corruption is involved in the crash mechanism, or more generally CWE-20: Improper Input Validation regarding how network data is processed. In terms of tactical mapping to the MITRE ATT&CK framework, this falls under T1499: Endpoint Denial of Service, specifically within the context of application layer attacks that aim to disrupt service availability rather than steal information or execute code. The attack vector typically involves Network Access (T1078) combined with Web Application Attacks (TA0002), where the adversary uses a web-based delivery mechanism to trigger the flaw in the client-side software. Understanding these classifications helps security teams prioritize patching efforts and configure endpoint detection systems to monitor for abnormal browser behavior indicative of such exploits, such as sudden process terminations or spikes in CPU usage associated with Firefox processes during network activity.
To mitigate this risk, organizations must ensure that all instances of Mozilla Firefox are updated to version 157 or later, where the underlying networking logic has been corrected to properly handle edge cases and malformed inputs without crashing. Administrators should enforce automatic update policies through group policy objects or mobile device management solutions to prevent users from remaining on vulnerable versions for extended periods. Additionally, deploying web content filtering solutions can help block access to known malicious domains that might host exploit kits targeting this specific vulnerability while patches are being deployed across the enterprise. Security awareness training should also be conducted to educate users about the risks of visiting untrusted websites, as social engineering remains a primary vector for delivering such exploits. Regular monitoring of browser crash reports and telemetry data can provide early indicators if new variants or related flaws emerge in future releases, allowing security teams to stay ahead of potential threats targeting the networking infrastructure of popular web browsers.