LLM05 · OWASP LLM Top 10

Improper Output Handling (LLM05)

Downstream systems trust LLM output and execute it without validation, leading to traditional injection vulnerabilities (XSS, SQL injection, command execution) being introduced through LLM-generated payloads.

Rank
LLM05 of 10
In the check
Not cited directly by a question
LLM01
Prompt Injection
LLM02
Sensitive Information Disclosure
LLM03
Supply Chain
LLM04
Data and Model Poisoning
LLM05
Improper Output Handling
LLM06
Excessive Agency
LLM07
System Prompt Leakage
LLM08
Vector and Embedding Weaknesses
LLM09
Misinformation
LLM10
Unbounded Consumption
Figure 1. The OWASP LLM Top 10, with LLM05 marked.
In practice

What it looks like in practice

Three shapes this risk takes in real deployments.

Example 1

An LLM writes a SQL query that's executed without parameterization.

Example 2

An LLM-generated HTML response is rendered without escaping, leading to stored XSS.

Example 3

An LLM writes shell commands that an automation framework executes.

Controls

Controls that close it

The controls the check looks for when this entry applies.

Treat LLM output as untrusted input to downstream systems

Output schema validation

Sandboxing for code-execution use cases

Output filtering and re-validation

Posture Check

Where the check cites it

The AI Posture Check cites OWASP LLM Top 10, including this entry, when placing you at Crawl, Walk, Run or Sprint.

The questions cite the control frameworks a regulator would expect you to hold: NIST AI RMF, ISO 42001 and the OWASP LLM Top 10. Your stage on the check is a starting point for an EU AI Act conformity review, not a substitute for one.

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