CWE-941 Base Incomplete

Incorrectly Specified Destination in a Communication Channel

This vulnerability occurs when an application establishes an outgoing communication channel but fails to correctly define or enforce the intended recipient. This misdirection can allow data to be…

Definition

What is CWE-941?

This vulnerability occurs when an application establishes an outgoing communication channel but fails to correctly define or enforce the intended recipient. This misdirection can allow data to be sent to an untrusted or malicious destination.
Attackers can exploit this flaw in two primary ways. First, if they can directly control the destination specification—such as in Server-Side Request Forgery (SSRF) or by spoofing UDP packets—they can redirect traffic to systems they control. This is often used to bypass firewalls, mask attack origins, or launch denial-of-service attacks. Second, the flaw can stem from the application itself incorrectly specifying the target due to misconfiguration, faulty parsing (like of email addresses or IPs), or insecure mechanisms like Android's sticky broadcasts. This unintentional misdirection can allow a malicious actor to intercept sensitive data meant for a trusted service, effectively spoofing it.
Real-world impact

Real-world CVEs caused by CWE-941

  • CVE-2013-5211

    composite: NTP feature generates large responses (high amplification factor) with spoofed UDP source addresses.

  • CVE-1999-0513

    Classic "Smurf" attack, using spoofed ICMP packets to broadcast addresses.

  • CVE-1999-1379

    DNS query with spoofed source address causes more traffic to be returned to spoofed address than was sent by the attacker.

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 Python

This code listens on a port for DNS requests and sends the result to the requesting address.

Vulnerable Python 
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
  sock.bind( (UDP_IP,UDP_PORT) )
  while true:
  		data = sock.recvfrom(1024)
  		if not data:
  			break
  		(requestIP, nameToResolve) = parseUDPpacket(data)
  		record = resolveName(nameToResolve)
  		sendResponse(requestIP,record)
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-941

  • 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-941

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-941 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-941?

This vulnerability occurs when an application establishes an outgoing communication channel but fails to correctly define or enforce the intended recipient. This misdirection can allow data to be sent to an untrusted or malicious destination.

How serious is CWE-941?

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-941?

MITRE lists the following affected platforms: Mobile.

How can I prevent CWE-941?

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-941?

Plexicus's SAST engine matches the data-flow signature for CWE-941 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-941?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/941.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-941

CWE-923 Parent

Improper Restriction of Communication Channel to Intended Endpoints

This vulnerability occurs when a system opens a communication channel for a sensitive task but fails to properly verify that it's actually…

CWE-1275 Sibling

Sensitive Cookie with Improper SameSite Attribute

This vulnerability occurs when a sensitive cookie does not have a secure SameSite attribute configured, leaving it exposed to cross-site…

CWE-291 Sibling

Reliance on IP Address for Authentication

This vulnerability occurs when a system uses a client's IP address as the sole or primary method to verify their identity.

CWE-297 Sibling

Improper Validation of Certificate with Host Mismatch

This vulnerability occurs when an application accepts a valid SSL/TLS certificate without properly verifying that it actually belongs to…

CWE-300 Sibling

Channel Accessible by Non-Endpoint

This vulnerability occurs when a system fails to properly verify who is on the other end of a communication link or to secure the channel…

CWE-419 Sibling

Unprotected Primary Channel

This vulnerability occurs when an application exposes a privileged administrative interface or restricted functionality through a primary…

CWE-420 Sibling

Unprotected Alternate Channel

This vulnerability occurs when an application secures its main communication path but leaves a backup or alternative channel with weaker…

CWE-940 Sibling

Improper Verification of Source of a Communication Channel

This vulnerability occurs when an application accepts incoming communication requests without properly checking where they originate from,…

CWE-942 Sibling

Permissive Cross-domain Security Policy with Untrusted Domains

This vulnerability occurs when a web application's cross-domain security policy, like a Content Security Policy (CSP), explicitly allows…

Resources

Further reading

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