CWE-545 Variant Deprecated

DEPRECATED: Use of Dynamic Class Loading

This entry has been retired. Its content is now covered elsewhere, primarily because it described a standard programming technique rather than a specific vulnerability and overlapped with other…

Definition

What is CWE-545?

This entry has been retired. Its content is now covered elsewhere, primarily because it described a standard programming technique rather than a specific vulnerability and overlapped with other existing weakness entries.
This CWE entry was deprecated because it focused on the mechanism of dynamic class loading itself, which is a legitimate and often necessary feature of modern programming languages and frameworks. The core security concern isn't the act of loading code dynamically, but how it's done—specifically, whether untrusted or unvalidated input controls what gets loaded. This distinction is crucial for developers to understand, as the feature is not inherently flawed. For practical security guidance, you should refer to related weaknesses that address the actual risks. These include using unvalidated input to influence class loading decisions (which can lead to path traversal or remote code execution) and the broader category of unsafe reflection. The retirement of this entry helps streamline the CWE list to focus on concrete, exploitable patterns rather than general programming concepts.
Real-world impact

Real-world CVEs caused by CWE-545

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-545

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Detection signals

How to detect CWE-545

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

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Frequently asked questions

Frequently asked questions

What is CWE-545?

This entry has been retired. Its content is now covered elsewhere, primarily because it described a standard programming technique rather than a specific vulnerability and overlapped with other existing weakness entries.

How serious is CWE-545?

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-545?

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

How can I prevent CWE-545?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

How does Plexicus detect and fix CWE-545?

Plexicus's SAST engine matches the data-flow signature for CWE-545 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-545?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/545.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-545

No related weaknesses indexed for this CWE.

Resources

Further reading

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