Adobe Fixes Actively Exploited Zero-Day in Acrobat Reader

Adobe disclosed an actively exploited zero-day (CVE-2026-34621) in Acrobat and Reader for Windows and macOS that is a Prototype Pollution flaw allowing attackers to execute JavaScript in a malicious PDF and achieve arbitrary code execution with user interaction; Adobe assigned Priority 1, updated the CVSS score (revised to 8.6 with a Local attack vector), listed affected builds, and published patched versions and mitigation guidance for enterprise and end users.