Adobe fixes PDF zero-day security bug that hackers have exploited for months

What Happened

Adobe fixed a zero-day vulnerability in Acrobat DC, Reader DC, and Acrobat 2024 that hackers exploited for at least four months. The flaw, tracked as CVE-2026-34621, allowed attackers to install malware remotely by sending malicious PDF files to Windows and macOS users. Security researcher Haifei Li discovered the exploit after a malicious PDF appeared on malware scanners in November 2025. Adobe urges users to update immediately.

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