CWE-1385 Variant Incomplete

Missing Origin Validation in WebSockets

This vulnerability occurs when a WebSocket connection is established without verifying the origin of incoming messages, allowing potentially malicious data from untrusted sources.

Definition

What is CWE-1385?

This vulnerability occurs when a WebSocket connection is established without verifying the origin of incoming messages, allowing potentially malicious data from untrusted sources.
WebSockets enable persistent, two-way communication between a client and server, which is ideal for real-time features. Unlike standard HTTP requests, these connections stay open and are not automatically restricted by browser security policies like the Same-Origin Policy (SOP) or Cross-Origin Resource Sharing (CORS). This means a WebSocket can receive messages from any origin unless the server explicitly validates where the connection is coming from. Without proper origin checks, attackers can exploit these open channels to launch powerful Cross-Site Request Forgery (CSRF) attacks or send malicious data. To prevent this, developers must implement server-side validation for every WebSocket connection request, ensuring it originates from a trusted and expected domain before allowing communication to proceed.
Real-world impact

Real-world CVEs caused by CWE-1385

  • CVE-2020-25095

    web console for SIEM product does not check Origin header, allowing Cross Site WebSocket Hijacking (CSWH)

  • CVE-2018-6651

    Chain: gaming client attempts to validate the Origin header, but only uses a substring, allowing Cross-Site WebSocket hijacking by forcing requests from an origin whose hostname is a substring of the valid origin.

  • CVE-2018-14730

    WebSocket server does not check the origin of requests, allowing attackers to steal developer's code using a ws://127.0.0.1:3123/ connection.

  • CVE-2018-14731

    WebSocket server does not check the origin of requests, allowing attackers to steal developer's code using a ws://127.0.0.1/ connection to a randomized port number.

  • CVE-2018-14732

    WebSocket server does not check the origin of requests, allowing attackers to steal developer's code using a ws://127.0.0.1:8080/ connection.

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-1385

  • Implementation Enable CORS-like access restrictions by verifying the 'Origin' header during the WebSocket handshake.
  • Implementation Use a randomized CSRF token to verify requests.
  • Implementation Use TLS to securely communicate using 'wss' (WebSocket Secure) instead of 'ws'.
  • Architecture and Design / Implementation Require user authentication prior to the WebSocket connection being established. For example, the WS library in Node has a 'verifyClient' function.
  • Implementation Leverage rate limiting to prevent against DoS. Use of the leaky bucket algorithm can help with this.
  • Implementation Use a library that provides restriction of the payload size. For example, WS library for Node includes 'maxPayloadoption' that can be set.
  • Implementation Treat data/input as untrusted in both directions and apply the same data/input sanitization as XSS, SQLi, etc.
Detection signals

How to detect CWE-1385

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-1385 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-1385?

This vulnerability occurs when a WebSocket connection is established without verifying the origin of incoming messages, allowing potentially malicious data from untrusted sources.

How serious is CWE-1385?

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-1385?

MITRE lists the following affected platforms: Web Server.

How can I prevent CWE-1385?

Enable CORS-like access restrictions by verifying the 'Origin' header during the WebSocket handshake. Use a randomized CSRF token to verify requests.

How does Plexicus detect and fix CWE-1385?

Plexicus's SAST engine matches the data-flow signature for CWE-1385 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-1385?

MITRE publishes the canonical definition at https://cwe.mitre.org/data/definitions/1385.html. You can also reference OWASP and NIST documentation for adjacent guidance.

Related weaknesses

Weaknesses related to CWE-1385

CWE-346 Parent

Origin Validation Error

This vulnerability occurs when an application fails to properly confirm the true origin of incoming data or communication, allowing…

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,…

Resources

Further reading

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