CWE-913 Class Incomplete

Improper Control of Dynamically-Managed Code Resources

This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.

Definition

What is CWE-913?

This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.
Many modern programming languages provide powerful features for dynamic code manipulation, allowing developers to generate or modify code, objects, and functions while the application is running. While these capabilities offer great flexibility and can speed up development, they introduce significant risk if an attacker can influence what gets created or changed. Without strict controls, an attacker could inject malicious logic, alter critical data structures, or bypass security checks by manipulating these dynamic resources. To prevent this, developers must implement strong validation, enforce strict access controls, and avoid using user input directly in dynamic code operations.
Real-world impact

Real-world CVEs caused by CWE-913

  • CVE-2022-2054

    Python compiler uses eval() to execute malicious strings as Python code.

  • CVE-2018-1000613

    Cryptography API uses unsafe reflection when deserializing a private key

  • CVE-2015-8103

    Deserialization issue in commonly-used Java library allows remote execution.

  • CVE-2006-7079

    Chain: extract used for register_globals compatibility layer, enables path traversal (CWE-22)

  • CVE-2012-2055

    Source version control product allows modification of trusted key using mass assignment.

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-913

  • Implementation For any externally-influenced input, check the input against an allowlist of acceptable values.
  • Implementation / Architecture and Design Refactor the code so that it does not need to be dynamically managed.
Detection signals

How to detect CWE-913

Fuzzing High

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Plexicus auto-fix

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Frequently asked questions

Frequently asked questions

What is CWE-913?

This vulnerability occurs when an application fails to properly secure access to code resources that can be created or altered at runtime, such as variables, functions, or objects.

How serious is CWE-913?

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-913?

MITRE has not specified affected platforms for this CWE — it can apply across most application stacks.

How can I prevent CWE-913?

For any externally-influenced input, check the input against an allowlist of acceptable values. Refactor the code so that it does not need to be dynamically managed.

How does Plexicus detect and fix CWE-913?

Plexicus's SAST engine matches the data-flow signature for CWE-913 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-913?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/913.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-913

CWE-664 Parent

Improper Control of a Resource Through its Lifetime

This vulnerability occurs when software fails to properly manage a resource throughout its entire lifecycle—from creation and active use…

CWE-118 Sibling

Incorrect Access of Indexable Resource ('Range Error')

This vulnerability occurs when software fails to properly check the boundaries of an indexed resource, like an array, buffer, or file,…

CWE-1229 Sibling

Creation of Emergent Resource

This vulnerability occurs when a system's normal operations unintentionally create new, exploitable resources that attackers can use to…

CWE-1250 Sibling

Improper Preservation of Consistency Between Independent Representations of Shared State

This vulnerability occurs when a system with multiple independent components (like distributed services or separate hardware units) each…

CWE-1329 Sibling

Reliance on Component That is Not Updateable

This vulnerability occurs when a product depends on a component that cannot be updated or patched to fix security flaws or critical bugs.

CWE-221 Sibling

Information Loss or Omission

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security…

CWE-372 Sibling

Incomplete Internal State Distinction

This vulnerability occurs when an application fails to accurately track its own operational state. The system incorrectly assumes it's in…

CWE-400 Sibling

Uncontrolled Resource Consumption

This vulnerability occurs when an application fails to properly manage a finite resource, allowing an attacker to exhaust it and cause a…

CWE-404 Sibling

Improper Resource Shutdown or Release

This vulnerability occurs when a program fails to properly close or release a system resource—like a file handle, database connection, or…

Resources

Further reading

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