CWE-252: Unchecked Return Value

The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.

Two common programmer assumptions are "this function call can never fail" and "it doesn't matter if this function call fails". If an attacker can force the function to fail or otherwise return a value that is not expected, then the subsequent program logic could lead to a vulnerability, because the product is not in a state that the programmer assumes. For example, if the program calls a function to drop privileges but does not check the return code to ensure that privileges were successfully dropped, then the program will continue to operate with the higher privileges.

Consequences

• Availability, Integrity: Unexpected State, DoS: Crash, Exit, or Restart

How to prevent it

• Implementation: Check the results of all functions that return a value and verify that the value is expected.
• Implementation: For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished [REF-1484].
• Implementation: Ensure that you account for all possible return values from the function.
• Implementation: When designing a function, make sure you return a value or throw an exception in case of an error.

Recent advisories

• GHSA-9v8h-qqgm-4m35 — Brotli: Out-of-bounds write in the Brotli decoder ("Node2Shell") also affects the PyPI Brotli package
• GHSA-rfgv-xxqx-mfg5 — undici vulnerable to Denial of Service via unrequested WebSocket subprotocol
• EEF-CVE-2026-78699 — rename_tenant returns :ok on a failed rename, enabling cross-tenant access in AshPostgres
• GHSA-9mr8-pwpw-3j2w — Microsoft Security Advisory CVE-2026-62909 – .NET Elevation of Privilege Vulnerability
• GHSA-qh5g-q395-cx4j — ImageMagick: Heap-use-after-free via XMP profile could result in a crash
• GHSA-jcqp-6r6f-3mfx — ImageMagick: Heap Buffer Over-Write in MIFF encoder when using LZMA compression
• GHSA-wh8p-h9hw-x2mc — uutils coreutils has an Unchecked Return Value Issue
• GHSA-wj8w-pjxf-9g4f — ImageMagick has uninitialized pointer dereference in JBIG decoder
• GHSA-wx95-c6cv-8532 — Nokogiri does not check the return value from xmlC14NExecute
• GHSA-f5x6-7qgp-jhf3 — ecrecover can return undefined data if signature does not verify
• GHSA-qv4q-mr5r-qprj — Unchecked return value from xmlTextReaderExpand
• GHSA-m69r-9g56-7mv8 — HashiCorp Consul vulnerable to authorization bypass
• GHSA-qh9x-gcfh-pcrw — OpenZeppelin Contracts's ERC165Checker may revert instead of returning false
• GHSA-xw6g-jjvf-wwf9 — Invalid file request can crash server
• GO-2021-0319 — Incorrect computation for some invalid field elements in crypto/elliptic

All advisories for CWE-252