Active Zero-Day Exploit Targeting Adobe Reader Users

### Executive Summary: A high-severity zero-day vulnerability in Adobe Reader is being actively exploited since at least December 2025 to achieve remote code execution via malicious PDF files. The exploit requires only that a user open a PDF, leverages memory corruption and in-memory execution to evade detection, targets Russian-language oil and gas-themed lures, affects the latest Adobe Reader version, and remains unpatched—suggesting involvement of well-resourced (possibly nation-state) actors.