Custodia vs Semgrep

Semgrep is a powerful pattern-matching SAST engine with community-written rules. But pattern matching can't understand AI semantics — prompt injection, LLM output trust, and AI compliance require behavioral analysis, not regex.

Semgrep rules match syntax patterns: sql"SELECT ... $USER_INPUT". But prompt injection is just string concatenation — f"{system_prompt}\n{user_input}"— which looks identical to safe code. Understanding whether that string becomes an LLM instruction requires semantic analysis, not pattern matching. No Semgrep rule can express "this user input is used as an LLM instruction."

No Semgrep Rule Can Detect Prompt Injection

Run a free Custodia scan and see what semantic AI analysis finds that pattern-matching tools miss — prompt injection, LLM output trust, and compliance gaps.