Run static analysis (SAST) on the codebase looking for the unsafe pattern in the data flow.
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
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web console for SIEM product does not check Origin header, allowing Cross Site WebSocket Hijacking (CSWH)
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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.
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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.
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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.
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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
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 pseudo
MITRE has not published a code example for this CWE. The pattern below is illustrative — see Resources for canonical references.
// 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
// 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
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-1385
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-1385?
How serious is CWE-1385?
What languages or platforms are affected by CWE-1385?
How can I prevent CWE-1385?
How does Plexicus detect and fix CWE-1385?
Where can I learn more about CWE-1385?
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
- MITRE — official CWE-1385 https://cwe.mitre.org/data/definitions/1385.html
- Cross-Site WebSocket Hijacking (CSWSH) https://christian-schneider.net/blog/cross-site-websocket-hijacking/
- WebSockets not Bound by SOP and CORS? Does this mean... https://blog.securityevaluators.com/websockets-not-bound-by-cors-does-this-mean-2e7819374acc
- How to secure your WebSocket connections https://www.freecodecamp.org/news/how-to-secure-your-websocket-connections-d0be0996c556/
- Cross-Site WebSocket Hijacking (CSWSH) https://medium.com/swlh/hacking-websocket-25d3cba6a4b9
- Testing for WebSockets security vulnerabilities https://portswigger.net/web-security/websockets
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