CVE-2026-12067

Missing exception handlers in AvastSvc native message dispatcher (ashServ.dll) on Windows allow a local, unprivileged attacker to crash the service by sending specially crafted JSON messages.



The vulnerability spans multiple handler pathways in the RPC-based native message protocol:

  *  Log_NmSvc.message handler: converts JSON fields to strings without type validation and without exception boundaries. 
  *  OpenInSz_NmSvc handler: converts URL and origin fields to strings without type checking, exposing an exception.
  *  OpenInSz_NmSvc.profile handler: converts the profile field to an integer without validation.


In all three cases, the exceptions are not caught by action-specific handlers and propagate up the dispatcher. The common root cause is the absence of try-catch blocks around JSON type conversions in the native message processing chain.