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Adobe Reader Zero-Day Exploited for Months Through Malicious PDFs

Researchers warn booby-trapped PDFs steal local data pending an Adobe patch.

Overview

  • EXPMON researcher Haifei Li confirmed an active Adobe Reader flaw that triggers on open and works on fully updated installs.
  • Heavily obfuscated JavaScript in the PDFs abuses privileged Acrobat APIs to read local files and send the data to attacker servers.
  • Analysts observed a recon stage that fingerprints systems to gate selective delivery of remote-control payloads.
  • Samples uploaded to VirusTotal in November 2025 indicate the campaign ran for months before researchers spotted it.
  • Adobe has not released a fix, so users should avoid untrusted PDFs and defenders can block traffic with the "Adobe Synchronizer" user-agent string.