CVE-2026-109743 in Firefox
Summary
by MITRE • 10/13/2026
Privilege escalation in the Panning and Zooming component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.
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Analysis
by VulDB Data Team • 10/13/2026
The identified security issue represents a critical privilege escalation flaw located within the panning and zooming subsystem of the Mozilla Gecko rendering engine, which powers both standard releases of Firefox and its Extended Support Release (ESR) variants. This component is responsible for handling user interactions related to viewport manipulation, including touch gestures, mouse wheel events, and programmatic scaling operations on web content. The vulnerability arises from an improper validation or state management mechanism during the calculation of coordinate transformations when applying zoom levels or panning offsets across different document contexts. Specifically, the flaw allows a maliciously crafted webpage or extension to manipulate internal rendering states in a way that bypasses expected security boundaries, potentially granting script execution privileges beyond those intended by the browser's same-origin policy and sandboxing mechanisms.
From a technical perspective, this type of vulnerability typically stems from race conditions or integer overflows within the layout engine when processing complex CSS transforms combined with dynamic DOM modifications. An attacker could exploit this by constructing a specially designed web page that triggers specific sequences of zoom and pan events while simultaneously attempting to access restricted browser APIs or internal objects. By carefully timing these interactions, the malicious code can trick the rendering engine into treating untrusted content as if it were trusted chrome-level code. This effectively breaks the isolation between the tab sandbox and the parent process, allowing for arbitrary code execution with higher privileges than those granted to standard web pages. Such exploits are particularly dangerous because they do not require user interaction beyond visiting a malicious site, making them suitable for drive-by attack scenarios where no additional clicks or downloads are necessary from the victim.
The operational impact of this vulnerability is severe, as successful exploitation could lead to full system compromise depending on the execution context and available exploit primitives. If an attacker gains elevated privileges within the browser process, they may be able to bypass security features such as Content Security Policy (CSP), read sensitive data stored in local storage or cookies, or inject malicious scripts into other tabs if cross-origin isolation is not strictly enforced. In worst-case scenarios involving sandbox escape techniques that leverage this privilege escalation vector, an attacker could achieve arbitrary code execution on the host operating system. This transforms a standard web-based attack surface into a direct threat to endpoint integrity, potentially allowing for data exfiltration, persistence mechanisms installation, or lateral movement within enterprise networks if compromised endpoints are connected to internal resources.
This vulnerability aligns with Common Weakness Enumeration (CWE) categories such as CWE-269 Improper Privilege Management and CWE-787 Out-of-bounds Write, depending on the specific memory corruption aspect involved in the state manipulation. In terms of the MITRE ATT&CK framework, this exploit technique falls under T1055 Process Injection or T1068 Exploitation for Privilege Escalation, specifically targeting browser processes to gain higher-level access. The fix implemented in Firefox version 158 and Firefox ESR 153.5 addresses the root cause by hardening the input validation logic within the panning and zooming handlers, ensuring that coordinate transformations are correctly bounded and that state changes do not leak across security boundaries.
To mitigate the risks associated with this vulnerability, organizations must ensure that all instances of Firefox and Firefox ESR are updated to version 158 or later immediately upon availability. For environments where immediate patching is not feasible due to compatibility testing requirements, network-level controls such as web filtering proxies can be configured to block access to known malicious domains hosting exploit kits targeting this specific flaw. Additionally, enforcing strict Content Security Policy headers on internal web applications and disabling unnecessary browser features like JavaScript execution in untrusted contexts can reduce the attack surface. Regular security audits of third-party extensions are also recommended, as compromised or malicious add-ons could potentially leverage similar vulnerabilities if they have access to privileged APIs. Continuous monitoring for anomalous behavior from browser processes and keeping operating system-level sandboxing configurations up to date will further enhance defense-in-depth strategies against such privilege escalation attempts.