CVE-2026-92055 in Firefox
Summary
by MITRE • 09/15/2026
Privilege escalation in the DevTools 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 issue represents a critical privilege escalation flaw located within the browser's Developer Tools subsystem, specifically affecting versions of Mozilla Firefox prior to version 156 and Firefox Extended Support Release (ESR) before 153.3. This vulnerability stems from an improper enforcement of access controls or boundary checks within the DevTools interface, which serves as a powerful debugging environment for web developers but also exposes sensitive browser internals to potential exploitation if not properly sandboxed. The core technical flaw likely involves a mechanism where unprivileged content scripts or maliciously crafted web pages can interact with privileged chrome-level APIs through the developer tools pipeline without adequate validation of their origin or permissions. This breakdown in isolation allows an attacker who has successfully executed arbitrary code within a webpage to bypass standard security boundaries and execute commands with higher privileges, effectively gaining control over browser settings, accessing sensitive user data, or manipulating the browsing session beyond what is permitted by normal web content policies.
From an operational perspective, this vulnerability poses a significant risk to users who frequently utilize developer tools for debugging complex applications or those who visit websites that may attempt to exploit such flaws through sophisticated social engineering or drive-by attack vectors. An attacker could leverage this privilege escalation to steal cookies containing session tokens, access local storage data intended only for the browser itself, or even modify security settings to disable protective features like cross-site scripting filters. The impact is particularly severe because developer tools are often used in trusted environments where users might inadvertently grant permissions that would otherwise be denied by default browser policies. By exploiting this flaw, an adversary can transition from a low-privilege state confined within the web content process to a high-privilege state with broader access to the user's system and personal information, thereby compromising confidentiality, integrity, and potentially availability depending on the specific exploitation path taken.
This type of vulnerability is commonly categorized under CWE-269, which denotes Improper Privilege Management, as it involves failing to restrict actions based on insufficiently trusted inputs or roles within the application architecture. In terms of offensive security frameworks such as MITRE ATT&CK, this flaw aligns with techniques related to privilege escalation and defense evasion, specifically those that involve abusing software vulnerabilities to gain elevated access without detection. The exploitation path typically falls under initial code execution followed by lateral movement within the local system context via browser process manipulation. It highlights the inherent risks in exposing powerful debugging interfaces to untrusted web content, necessitating rigorous sandboxing strategies and strict separation of concerns between developer-facing tools and core browsing functionality.
To mitigate this risk, users must ensure that their browsers are updated to Firefox version 156 or later, including the ESR branch update to 153.3, which contains the necessary patches to correct the access control logic within the DevTools component. Organizations should enforce automated patch management policies to guarantee timely deployment of security updates across all endpoints running affected browser versions. Additionally, administrators can consider implementing content security policies that restrict the use of developer tools in production environments where such functionality is not strictly required for business operations. Regular auditing of installed extensions and disabling unnecessary add-ons further reduces the attack surface by limiting potential vectors through which malicious scripts might attempt to interact with vulnerable components. Continuous monitoring for anomalous browser behavior and keeping threat intelligence feeds updated regarding known exploitation techniques related to browser privilege escalation will also aid in early detection and response should a similar vulnerability be discovered or actively exploited in the wild.