This cybersecurity brief for October 21, 2026, covers several critical developments. Details of two maximum-severity PHP vulnerabilities, dubbed "PHP2Shell," were leaked ahead of patches, with active exploitation already observed. CISA added six flaws to its KEV catalog, including the "Plex2Shell" chain. Meanwhile, the Lazarus APT group launched a new campaign using post-quantum cryptography, and a joint advisory warned of the highly active SafePay ransomware gang. Other major incidents include a ConnectWise supply chain attack impacting Microsoft 365 customers and an emergency revocation of eMudhra certificates due to weak private keys.
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