CVE-2026-5426

A critical ViewState deserialization vulnerability (CVE-2026-5426) in the KnowledgeDeliver LMS allows unauthenticated remote code execution due to shared ASP.NET machine keys across deployments. Threat actors are actively exploiting this flaw to deploy the BLUEBEAM in-memory web shell and modify application JavaScript, ultimately distributing targeted Cobalt Strike BEACON payloads to end-users visiting the compromised sites.