Description

Privilege escalation in the Enterprise Policies component. This vulnerability was fixed in Firefox 156 and Firefox ESR 153.3.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-09-15T13:17:02.153Z",
  "pubdate": "2026-09-15T13:17:02.153Z",
  "executiveSummary": "This vulnerability report details a critical privilege escalation flaw identified within the Enterprise Policies component of Mozilla Firefox and Firefox Extended Support Release (ESR). Enterprise Policies are utilized by system administrators to configure and restrict browser behavior across deployment environments. A vulnerability within this mechanism allows an attacker to bypass established security boundaries, leading to an unauthorized elevation of privileges. This security flaw affects versions of Firefox prior to version 156 and Firefox ESR prior to version 153.3. If exploited successfully, an attacker could abuse the policy engine to execute commands or access resources with elevated permissions, potentially compromising the underlying host system. Depending on the environment configuration, the exploit could allow local or low-privileged users to override administrative restrictions, leading to full system compromise or unauthorized access to sensitive user data. The exploitation of this vulnerability typically requires some degree of local access or the ability to influence the browser's execution environment, making it a severe vector for post-exploitation lateral movement within enterprise networks. To mitigate these risks, organizations must prioritize upgrading to the patched releases (Firefox 156 and Firefox ESR 153.3), as there are no viable long-term workarounds that preserve full enterprise functionality.",
  "technicalDetails": "The Enterprise Policies engine in Mozilla Firefox is designed to ingest policy files (such as policies.json or group policy objects) to enforce administrative controls on browser execution. These controls include restricting access to specific URLs, disabling certain developer tools, forcing extension installations, and managing security settings. A logic flaw or validation failure within this component allows an attacker to manipulate or bypass these restrictions. Because the browser engine runs with specific OS-level privileges and interacts closely with the host operating system, bypassing policy constraints can allow an attacker to transition from a restricted user context to a higher-privilege execution state.\nTo execute this exploit, an attacker typically targets the parsing or enforcement phase of the Enterprise Policies. Under normal operations, the policy engine initializes during browser startup and locks down specific APIs and preferences. However, due to the vulnerability, certain parameters or policy definitions are handled incorrectly. An attacker capable of placing a malformed or specifically crafted policy configuration file, or leveraging an existing application vulnerability to interact with the policy parsing APIs, can cause the engine to misinterpret instructions. This misinterpretation can lead to the disabling of security sandboxes, unauthorized execution of privileged XPCOM or WebExtensions APIs, or the execution of arbitrary code under the context of the elevated browser process.\nThe typical attack path involves several key steps. First, an attacker establishes initial execution access on the target system with low privileges. Next, the attacker identifies that Firefox or Firefox ESR is deployed with Enterprise Policies enabled. The attacker then injects or manipulates policy configurations, or exploits a runtime parsing vulnerability in the browser's policy ingestion routine. Upon browser launch or policy reload, the validation logic fails to properly sanitize the input, allowing the execution of restricted actions or scripts. Finally, the attacker leverages the elevated context of the browser process to execute unauthorized commands, effectively escalating privileges.\nOnce privilege escalation is achieved, the security boundaries enforced by the operating system or the browser container are broken. The attacker can read, write, or delete sensitive system files, modify browser binaries, install malicious extensions silently, or access restricted network segments. This vulnerability presents a significant risk in multi-user enterprise environments or terminal server setups where low-privilege users are intended to be strictly isolated from administrative control. The fix implemented in Firefox 156 and Firefox ESR 153.3 hardens the validation routines of the Enterprise Policies component, preventing unauthorized manipulation and ensuring strict policy enforcement boundaries are maintained."
}