Threat actors have been exploiting a previously unknown zero-day vulnerability in Adobe Reader using maliciously crafted PDF documents since at least December 2025.
The finding, detailed by EXPMON’s Haifei Li, has been described as a highly-sophisticated PDF exploit. The artifact („Invoice540.pdf“) first appeared on the VirusTotal platform on November 28, 2025. A second 
https://thehackernews.com/2026/04/adobe-reader-zero-day-exploited-via.html