Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
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
-
composite: NTP feature generates large responses (high amplification factor) with spoofed UDP source addresses.
-
Classic "Smurf" attack, using spoofed ICMP packets to broadcast addresses.
-
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
Identify a code path that handles untrusted input without validation.
- 2
Craft a payload that exercises the unsafe behavior — injection, traversal, overflow, or logic abuse.
- 3
Deliver the payload through a normal request and observe the application's reaction.
- 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.
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
// 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
Run dynamic application security testing against the live endpoint.
Watch runtime logs for unusual exception traces, malformed input, or authorization bypass attempts.
Code review: flag any new code that handles input from this surface without using the validated framework helpers.
CWE-941
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Frequently asked questions What is CWE-941?
How serious is CWE-941?
What languages or platforms are affected by CWE-941?
How can I prevent CWE-941?
How does Plexicus detect and fix CWE-941?
Where can I learn more about CWE-941?
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
Ready to validate what matters?
Ready to validate what matters?
Plexicus is Proof-Driven AppSec: validated findings, contextual understanding, and reviewed remediation — anchored in evidence, scoped with you.