Adobe Patches Actively Exploited Acrobat Reader Flaw CVE-2026-34621

Adobe released emergency updates to address CVE-2026-34621, a critical prototype-pollution vulnerability in Acrobat and Acrobat Reader that can lead to arbitrary code execution when victims open specially crafted PDF documents. Adobe confirmed active in-the-wild exploitation, provided fixed builds for affected Windows and macOS versions, and credited researcher Haifei Li for disclosing exploit details; evidence suggests exploitation may date back to December 2025.