The Frontmatter Is the Vulnerability: AST04 Insecure Metadata and YAML Deserialization
AST04 of the OWASP Agentic Skills Top 10: skill metadata is attacker-controlled input - brand impersonation, permission understating, risk-tier spoofing, invisible-character injections, and YAML !!python/object deserialization that executes code at parse time, before approval. Safe-parser and schema controls explained.