
Windows 0-Click Flaw Bypasses SmartScreen; Patch Leaves NTLM Exposure
APT28 exploited a Windows Shell 0-click vulnerability chain (CVE-2026-21510 and CVE-2026-21513) via a weaponized LNK file to bypass Defender SmartScreen and load a CPL component without user interaction; Microsoft patched the RCE path in the April 2026 Patch Tuesday by adding ControlPanelLinkSite and a trust-verification flag, but a residual flaw (CVE-2026-32202) allows NTLM authentication to be triggered during UNC-path resolution when opening a folder containing the LNK, enabling credential exposure. Defenders should apply the April 2026 updates immediately, monitor outbound SMB traffic, enforce NTLMv2 or Kerberos, and perform regression testing to prevent patch regressions.











