Improper Output Handling

Model-generated content is passed downstream — into a shell, a database query, a browser, another agent — without adequate validation or sanitisation, so the model's text becomes an execution path. In a multi-agent system: An agent's generated SQL fragment is concatenated directly into a live query, and an injected character lets the query read outside the c…

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Concept

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Classification level

Structure

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In brief

Improper Output Handling in brief

Improper output handling is the unchecked passing of model or agent output to downstream systems.

Where does it come from?

The risk comes from classic application security, where unvalidated inputs and outputs cause injection and execution failures; OWASP explicitly describes this transfer for LLM applications.

The mental model

An output is first treated as untrusted data, validated, and constrained to an allowed structure and effect. Only then may it reach SQL, shell commands, browser actions, or further agent flows.

Key building blocks

Core idea

Mechanism

In a multi-agent system: An agent's generated SQL fragment is concatenated directly into a live query, and an injected character lets the query read outside the caller's own records.

Practice context

Primary mitigation: Validate every model-generated payload with Output Validation / Schema Enforcement before use, and run any generated code inside Sandbox Execution.

When is it useful?

The pattern matters wherever generated text can trigger actions. Schema validation, output encoding, command allowlists, and human approval reduce risk; plausibility checks alone are rarely sufficient.

OWASP LLM05 Improper Output Handling

Why is this building block relevant?

Model-generated content is passed downstream — into a shell, a database query, a browser, another agent — without adequate validation or sanitisation, so the model's text becomes an execution path.