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Application & OT Security · Intermediate

Mishandling of Exceptional Conditions

OWASP Top 10 2025 category (A10) for improper error handling, failing open and logic errors under abnormal conditions.

Definition

Covers failure to prevent, detect or respond to unusual conditions, such as unchecked return values, exceptions that leave transactions half-complete, fail-open authorization and verbose error leakage. Mitigations include centralized exception handling, failing closed, rolling back transactions, input limits and testing error paths.

Example

An exception in the payment authorization check is caught and ignored, so the order proceeds unpaid.

Exam tip

New in 2025; think 'fail closed' and 'test the error paths'.

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