CWE-474 Base Draft

Use of Function with Inconsistent Implementations

This vulnerability occurs when code relies on a function whose behavior changes across different operating systems or versions, leading to unpredictable security risks when the software runs in an…

Definition

What is CWE-474?

This vulnerability occurs when code relies on a function whose behavior changes across different operating systems or versions, leading to unpredictable security risks when the software runs in an unexpected environment.
Functions can behave differently depending on where your code runs. These inconsistencies might involve how parameters are interpreted, what return codes mean, or whether the function even exists on a given platform. When you build or deploy software in an environment other than the one you tested in, these subtle differences can cause crashes, logic errors, or unexpected behavior that attackers might exploit. Some implementations of a function might have known security flaws, while others are safe. This means your application's security could depend entirely on the underlying system it's running on, creating a hidden risk. To avoid this, never assume a function behaves identically everywhere; always check documentation for the specific platforms you target and consider using standardized, portable alternatives where possible.
Real-world impact

Real-world CVEs caused by CWE-474

No public CVE references are linked to this CWE in MITRE's catalog yet.

How attackers exploit it

Step-by-step attacker path

  1. 1

    Identify a code path that handles untrusted input without validation.

  2. 2

    Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.

  3. 3

    Deliver the payload through a normal request and observe the application's reaction.

  4. 4

    Iterate until the response leaks data, executes attacker code, or escalates privileges.

Vulnerable code example

Vulnerable pseudo

MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.

Vulnerable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Secure code example

Secure pseudo

Secure pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Prevention checklist

How to prevent CWE-474

  • Architecture and Design / Requirements Do not accept inconsistent behavior from the API specifications when the deviant behavior increase the risk level.
Detection signals

How to detect CWE-474

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 searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

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Frequently asked questions

Frequently asked questions

What is CWE-474?

This vulnerability occurs when code relies on a function whose behavior changes across different operating systems or versions, leading to unpredictable security risks when the software runs in an unexpected environment.

How serious is CWE-474?

MITRE has not published a likelihood-of-exploit rating for this weakness. Treat it as medium-impact until your threat model proves otherwise.

What languages or platforms are affected by CWE-474?

MITRE lists the following affected platforms: C, PHP.

How can I prevent CWE-474?

Do not accept inconsistent behavior from the API specifications when the deviant behavior increase the risk level.

How does Plexicus detect and fix CWE-474?

Plexicus's SAST engine matches the data-flow signature for CWE-474 on every commit. When a match is found, our Codex Remedium agent opens a fix PR with the corrected code, tests, and a one-line summary for the reviewer.

Where can I learn more about CWE-474?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/474.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-474

CWE-758 Parent

Reliance on Undefined, Unspecified, or Implementation-Defined Behavior

This weakness occurs when software depends on specific behaviors of an API, data structure, or system component that are not formally…

CWE-1038 Sibling

Insecure Automated Optimizations

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CWE-1102 Sibling

Reliance on Machine-Dependent Data Representation

This weakness occurs when software directly depends on how a specific machine, processor, or operating system represents data in memory.…

CWE-1103 Sibling

Use of Platform-Dependent Third Party Components

This weakness occurs when software depends on third-party libraries or components that behave differently or lack support across various…

CWE-1105 Sibling

Insufficient Encapsulation of Machine-Dependent Functionality

This weakness occurs when an application relies on hardware-specific or platform-dependent features but fails to isolate that code from…

CWE-562 Sibling

Return of Stack Variable Address

This vulnerability occurs when a function returns a pointer to its own local variable. Since that variable's memory is on the stack, the…

CWE-587 Sibling

Assignment of a Fixed Address to a Pointer

This vulnerability occurs when code explicitly assigns a hardcoded memory address to a pointer, instead of using a dynamic or null value.

CWE-588 Sibling

Attempt to Access Child of a Non-structure Pointer

This vulnerability occurs when code incorrectly treats a pointer to a basic data type (like an integer) as if it points to a structured…

CWE-589 Child

Call to Non-ubiquitous API

This vulnerability occurs when software relies on an operating system function that isn't available on all versions of the target…

Resources

Further reading

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