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Base · Medium

CWE-584: Return Inside Finally Block

The code has a return statement inside a finally block, which will cause any thrown exception in the try block to be discarded.

CWE-584 · Base Level ·1 Mitigations

Description

The code has a return statement inside a finally block, which will cause any thrown exception in the try block to be discarded.

Potential Impact

Other

Alter Execution Logic

Demonstrative Examples

In the following code excerpt, the IllegalArgumentException will never be delivered to the caller. The finally block will cause the exception to be discarded.
Bad
try {...throw IllegalArgumentException();}finally {return r;}

Mitigations & Prevention

Implementation

Do not use a return statement inside the finally block. The finally block should have "cleanup" code.

Detection Methods

  • Automated Static Analysis High — Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then sea

CWE-705: Incorrect Control Flow Scoping

The product does not properly return control flow to the proper location after it has completed a task or detected an un...

Taxonomy Mappings

  • The CERT Oracle Secure Coding Standard for Java (2011): ERR04-J — Do not complete abruptly from a finally block
  • The CERT Oracle Secure Coding Standard for Java (2011): ERR05-J — Do not let checked exceptions escape from a finally block
  • Software Fault Patterns: SFP6 — Incorrect Exception Behavior

Frequently Asked Questions

What is CWE-584?

CWE-584 (Return Inside Finally Block) is a software weakness identified by MITRE's Common Weakness Enumeration. It is classified as a Base-level weakness. The code has a return statement inside a finally block, which will cause any thrown exception in the try block to be discarded.

How can CWE-584 be exploited?

Attackers can exploit CWE-584 (Return Inside Finally Block) to alter execution logic. This weakness is typically introduced during the Implementation phase of software development.

How do I prevent CWE-584?

Key mitigations include: Do not use a return statement inside the finally block. The finally block should have "cleanup" code.

What is the severity of CWE-584?

CWE-584 is classified as a Base-level weakness (Medium abstraction). Its actual severity depends on the specific context and how the weakness manifests in your application.