CWE-694 Base Incomplete

Use of Multiple Resources with Duplicate Identifier

This vulnerability occurs when a system uses multiple resources that can share the same identifier, even though the application logic requires each identifier to be unique.

Definition

What is CWE-694?

This vulnerability occurs when a system uses multiple resources that can share the same identifier, even though the application logic requires each identifier to be unique.
When software is designed to assume that identifiers like file handles, session tokens, or database keys are always unique, sharing identifiers between resources breaks this fundamental assumption. This can happen due to race conditions, insufficient validation, or flawed resource allocation logic, creating a situation where the application cannot reliably distinguish between different objects or data streams. An attacker can exploit this by forcing two distinct resources—such as files, memory blocks, or user sessions—to be referenced by the same identifier. This causes the application to perform actions on the wrong resource, potentially leading to data corruption, information disclosure, or privilege escalation, as the system's control flow is diverted based on a compromised identifier.
Real-world impact

Real-world CVEs caused by CWE-694

  • CVE-2013-4787

    chain: mobile OS verifies cryptographic signature of file in an archive, but then installs a different file with the same name that is also listed in the archive.

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 XML

These two Struts validation forms have the same name.

Vulnerable XML 
<form-validation> 
  	 <formset> 
  		 <form name="ProjectForm"> ... </form>
  		 <form name="ProjectForm"> ... </form> 
  	 </formset> 
   </form-validation>
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-694

  • Architecture and Design Where possible, use unique identifiers. If non-unique identifiers are detected, then do not operate any resource with a non-unique identifier and report the error appropriately.
Detection signals

How to detect CWE-694

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-694 and opens a fix PR in under 60 seconds.

Codex Remedium scans every commit, identifies this exact weakness, and ships a reviewer-ready pull request with the patch. No tickets. No hand-offs.

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Frequently asked questions

Frequently asked questions

What is CWE-694?

This vulnerability occurs when a system uses multiple resources that can share the same identifier, even though the application logic requires each identifier to be unique.

How serious is CWE-694?

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-694?

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

How can I prevent CWE-694?

Where possible, use unique identifiers. If non-unique identifiers are detected, then do not operate any resource with a non-unique identifier and report the error appropriately.

How does Plexicus detect and fix CWE-694?

Plexicus's SAST engine matches the data-flow signature for CWE-694 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-694?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/694.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-694

CWE-99 Parent

Improper Control of Resource Identifiers ('Resource Injection')

This vulnerability occurs when an application accepts user input as a resource identifier (like a file path or port number) without proper…

CWE-641 Sibling

Improper Restriction of Names for Files and Other Resources

This vulnerability occurs when an application creates file or resource names using unvalidated user input, failing to properly limit what…

CWE-914 Sibling

Improper Control of Dynamically-Identified Variables

This vulnerability occurs when an application fails to properly secure access to variables whose names are determined at runtime, allowing…

CWE-102 Child

Struts: Duplicate Validation Forms

This vulnerability occurs when an application defines multiple Struts validation forms with identical names. The framework then…

CWE-462 Child

Duplicate Key in Associative List (Alist)

This vulnerability occurs when an associative list (alist) contains duplicate keys, which can cause unexpected behavior when software…

Resources

Further reading

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