CVE-2026-117977 in Firefox
Summary
by MITRE • 10/27/2026
Other issue in the Console component. This vulnerability was fixed in Firefox 159 and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw resides within the Console component of Mozilla Firefox, specifically affecting versions prior to Firefox 159 and Firefox Extended Support Release (ESR) 153.6. This vulnerability represents a class of issues often associated with improper handling of internal state or data structures during the processing of console output messages. While specific technical details regarding the exact mechanism are not fully disclosed in public advisories, such vulnerabilities typically involve memory corruption, logic errors, or cross-site scripting vectors that can be triggered through maliciously crafted web content interacting with browser developer tools or logging mechanisms. The Console component is a critical interface for developers and users to view diagnostic information, making it a potential target for attackers seeking to exploit trust relationships between the user agent and loaded web pages.
From a technical perspective, vulnerabilities in console-related components often stem from insufficient validation of input data before rendering or processing it within the browser's internal logging subsystems. This can lead to scenarios where an attacker injects malicious payloads that are executed when the console is accessed or updated. In some cases, these flaws may allow for cross-site scripting (XSS), enabling the theft of sensitive user data such as session cookies, authentication tokens, or personally identifiable information. Alternatively, more severe memory safety issues could potentially lead to arbitrary code execution if the vulnerability involves buffer overflows or use-after-free conditions within the native C++ code underlying the Firefox engine. The presence of such a flaw underscores the complexity of maintaining secure interfaces between high-level JavaScript environments and low-level browser components.
The operational impact of this vulnerability is significant for users who rely on Firefox for development work, security auditing, or general browsing where console interactions are frequent. An exploited vulnerability could allow an attacker to bypass same-origin policies, leading to unauthorized access to private data stored within the browser context. For enterprise environments utilizing Firefox ESR, such vulnerabilities pose a risk to organizational security postures by potentially compromising endpoint integrity through drive-by attacks or malicious extensions that interact with developer tools. The lack of immediate patching in older versions leaves users exposed to these risks until they upgrade to the fixed releases.
Mitigation strategies primarily involve ensuring that all instances of Firefox are updated to version 159 for standard release channels and version 153.6 for Extended Support Release channels. Organizations should enforce automated update policies to minimize the window of exposure. Additionally, users can reduce risk by disabling unnecessary browser features or extensions that interact with console outputs if they cannot immediately patch their systems. Security teams should monitor for indicators of compromise related to exploitation attempts targeting developer tools and consider implementing content security policies that restrict inline scripts and external resource loading where feasible.
This issue aligns with common vulnerability classifications such as CWE-79, which covers Improper Neutralization of Input During Web Page Generation (Cross-site Scripting), or potentially CWE-120 if it involves buffer overflows in the underlying memory management. In terms of attack vectors, this falls under MITRE ATT&CK techniques related to Client-side Execution and Data Exfiltration from Local Systems via Browser-based Attacks. The resolution highlights Mozilla's commitment to addressing security flaws in core browser components that facilitate developer interactions, ensuring that tools intended for debugging do not become vectors for malicious activity. Continuous monitoring of vendor advisories and prompt application of patches remain the most effective defense against such vulnerabilities.