Common LLM Security

OWASP LLM Top 10 Security Checklist (2025)

Priority: P0 (CRITICAL)

Implementation Guidelines

• Check LLM01 first: Prompt injection #1 LLM finding — any user input concatenated directly into prompt string immediate P0.
• Check LLM06 next: Agent tools with write/delete/execute capabilities without confirmation P0.
• Mark each item: ✅ not affected | ⚠️ needs review | 🔴 confirmed finding.
• P0 finding caps Security score at 40/100 — not skip any item.
• See references/owasp-llm.md for full detection signals.

OWASP LLM Top 10 (2025)

| ID | Risk | Key Detection Signal |

| ----- | ---- | -------------------- |

| LLM01 | Prompt Injection | User input string-concatenated into prompt. Retrieved docs inserted into system turn. |

| LLM02 | Sensitive Information Disclosure | PII or credentials passed into prompt context. LLM response logged without redaction. |

| LLM03 | Supply Chain | Unverified model weights or plugins. Third-party agent added without trust review. |

| LLM04 | Data & Model Poisoning | User-controlled data written to training sets or embedding stores without validation. |

| LLM05 | Improper Output Handling | LLM output used directly in DOM sink, SQL query, shell command, or redirect URL. |

| LLM06 | Excessive Agency | Agent tool with write/delete/network access — no human-in--loop confirmation. |

| LLM07 | System Prompt Leakage | System prompt content returned via tool output, error message, or API response. |

| LLM08 | Vector & Embedding Weaknesses | User text injected into vector store without sanitization. No tenant namespace isolation. |

| LLM09 | Misinformation | LLM output used for critical decisions (medical, financial, legal) without verification. |

| LLM10 | Unbounded Consumption | No max_tokens on LLM call. No rate limit on invocations. Agent loop without depth cap. |

Anti-Patterns

• No prompt concat: Pass user input as separate user turn, never interpolated into system prompts.
• No raw LLM output in sinks: Sanitize LLM responses before writing to DOM, queries, or shell.
• No uncapped agent loops: Every agentic recursion must enforce max iteration/depth limit.

References

• OWASP LLM — Full Detection Signals — load when auditing any LLM client code

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

• sanitize