Description

Privilege escalation in the Request Handling component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-18T13:17:32.493Z",
  "pubdate": "2026-08-18T13:17:32.493Z",
  "executiveSummary": "A privilege escalation vulnerability has been identified within the Request Handling component of Firefox. This security flaw allows malicious entities to execute arbitrary actions with elevated privileges, bypassing standard security boundaries enforced by the application architecture.\nThe vulnerability directly impacts Firefox version 154 and Firefox ESR version 153.1 prior to their respective patches. Successful exploitation compromises the integrity and confidentiality of the underlying host system, potentially enabling threat actors to escalate privileges beyond their authorized context.\nRisk implications include unauthorized access to sensitive resources and potential system compromise depending on the user context and system configuration. The vulnerability requires the target application to process maliciously crafted inputs or interactions within the vulnerable Request Handling subsystem.\nMitigation requires immediate application of official software updates provided by Mozilla, specifically upgrading to Firefox 154, Firefox ESR 153.1, or subsequent secured releases where the underlying flaw in the Request Handling component is fully addressed.",
  "technicalDetails": "The vulnerability resides within the Request Handling component of Firefox, stemming from improper validation and management of operational context during transaction processing. Specifically, insufficient bounds checking and flawed state transitions allow an untrusted processing flow to inherit broader access rights than initially allocated.\nExploitation of this privilege escalation vector typically involves an attacker interacting with vulnerable internal interfaces or manipulating data structures processed by the Request Handling subsystem. By inducing anomalous execution states, unauthorized code or request sequences can execute within a context possessing heightened execution privileges.\nThe affected versions include Firefox prior to version 154 and Firefox ESR prior to version 153.1. The flaw exists within the compiled binaries of the browser engine where the Request Handling component executes core logic.\nAttack flow typically proceeds as follows: First, the attacker identifies or introduces an operational trigger that engages the vulnerable Request Handling logic. Second, input vectors or internal message parameters are manipulated to subvert normal control flow mechanisms. Third, due to inadequate sanitization and privilege boundary enforcement within the component, the execution context fails to downgrade or isolate the operation. Finally, the attacker achieves elevated execution capabilities, enabling unauthorized system interactions or data access pertinent to the compromised privilege tier."
}