Sensitive Cookie with Improper SameSite Attribute

The SameSite attribute for sensitive cookies is not set, or an insecure value is used.


The SameSite attribute controls how cookies are sent for cross-domain requests. This attribute may have three values: 'Lax', 'Strict', or 'None'. If the 'None' value is used, a website may create a cross-domain POST HTTP request to another website, and the browser automatically adds cookies to this request. This may lead to Cross-Site-Request-Forgery (CSRF) attacks if there are no additional protections in place (such as Anti-CSRF tokens).


The following examples help to illustrate the nature of this weakness and describe methods or techniques which can be used to mitigate the risk.

Note that the examples here are by no means exhaustive and any given weakness may have many subtle varieties, each of which may require different detection methods or runtime controls.

Example One

In this example, a cookie is used to store a session ID for a client's interaction with a website. The snippet of code below establishes a new cookie to hold the sessionID.

let sessionId = generateSessionId()
let cookieOptions = { domain: '' }
response.cookie('sessionid', sessionId, cookieOptions)

Since the sameSite attribute is not specified, the cookie will be sent to the website with each request made by the client. An attacker can potentially perform a CSRF attack by using the following malicious page:


  <form id=evil action="http://local:3002/setEmail" method="POST">

    <input type="hidden" name="newEmail" value="" />



When the client visits this malicious web page, it submits a '/setEmail' POST HTTP request to the vulnerable website. Since the browser automatically appends the 'sessionid' cookie to the request, the website automatically performs a 'setEmail' action on behalf of the client.

To mitigate the risk, use the sameSite attribute of the 'sessionid' cookie set to 'Strict'.

let sessionId = generateSessionId()
let cookieOptions = { domain: '', sameSite: 'Strict' }
response.cookie('sessionid', sessionId, cookieOptions)

See Also

Comprehensive Categorization: Access Control

Weaknesses in this category are related to access control.

OWASP Top Ten 2021 Category A01:2021 - Broken Access Control

Weaknesses in this category are related to the A01 category "Broken Access Control" in the OWASP Top Ten 2021.

Comprehensive CWE Dictionary

This view (slice) covers all the elements in CWE.

Weaknesses Introduced During Implementation

This view (slice) lists weaknesses that can be introduced during implementation.

Common Weakness Enumeration content on this website is copyright of The MITRE Corporation unless otherwise specified. Use of the Common Weakness Enumeration and the associated references on this website are subject to the Terms of Use as specified by The MITRE Corporation.