CWE-1024 Base Incomplete

Comparison of Incompatible Types

This vulnerability occurs when code directly compares two values of fundamentally different data types, which can lead to unreliable or incorrect results because the comparison logic doesn't handle…

Definition

What is CWE-1024?

This vulnerability occurs when code directly compares two values of fundamentally different data types, which can lead to unreliable or incorrect results because the comparison logic doesn't handle the type mismatch properly.
In strictly-typed languages like C or C++, developers might try to force a comparison by casting one value to match the other's type. However, this manual conversion doesn't guarantee a semantically correct or safe comparison, as the underlying meaning or representation of the data may be distorted during the cast, leading to logic errors. In loosely-typed languages like JavaScript or PHP, the problem often happens implicitly. The language's internal type coercion rules automatically convert values during comparison, which can produce surprising outcomes—like a string "123" being treated as the number 123, or "0" being evaluated as false. Developers must explicitly validate and convert types before comparing to ensure the logic behaves as intended.
Real-world impact

Real-world CVEs caused by CWE-1024

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-1024

  • Testing Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.
Detection signals

How to detect CWE-1024

SAST High

Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.

DAST Moderate

Run dynamic application security testing against the live endpoint.

Runtime Moderate

Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.

Code review Moderate

Code review: flag any new code that handles input from this surface without using the validated framework helpers.

Plexicus auto-fix

Plexicus auto-detects CWE-1024 and opens a fix PR in under 60 seconds.

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Frequently asked questions

Frequently asked questions

What is CWE-1024?

This vulnerability occurs when code directly compares two values of fundamentally different data types, which can lead to unreliable or incorrect results because the comparison logic doesn't handle the type mismatch properly.

How serious is CWE-1024?

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-1024?

MITRE lists the following affected platforms: JavaScript, PHP.

How can I prevent CWE-1024?

Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.

How does Plexicus detect and fix CWE-1024?

Plexicus's SAST engine matches the data-flow signature for CWE-1024 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-1024?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1024.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1024

CWE-697 Parent

Incorrect Comparison

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CWE-1023 Sibling

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CWE-1025 Sibling

Comparison Using Wrong Factors

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CWE-1039 Sibling

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CWE-1077 Sibling

Floating Point Comparison with Incorrect Operator

This vulnerability occurs when code compares two floating-point numbers using direct equality operators (like == or !=) without accounting…

CWE-1254 Sibling

Incorrect Comparison Logic Granularity

This vulnerability occurs when a system compares sensitive data, like passwords or authentication tokens, piece-by-piece instead of as a…

CWE-183 Sibling

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CWE-185 Sibling

Incorrect Regular Expression

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CWE-581 Sibling

Object Model Violation: Just One of Equals and Hashcode Defined

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Resources

Further reading

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