Cookies SameSite flag invalid

OWASP 2013-A5 OWASP 2017-A6 OWASP 2021-A5 OWASP 2019-API7 OWASP PC-C1 CWE-16 ISO27001-A.14.2.5 WASC-15 WSTG-SESS-02

Cookies are used to manage state, handle logins or to track you for advertising purposes and should be kept safe. The process involved in setting cookie are:-

  1. The server asks your browser to set a cookie.
  2. It gives a name, value and other parameters.
  3. Browser stores the data in disk or memory. This feature depends on the cookie type.

SameSite prevents a browser from causing cross-site scripting attacks. The main goal of this flag is to reduce the chance of cross-origin information leakage to zero. It additionally provides some protection against attacks like cross-site request forgery attacks.

The goals of the SameSite flag are to Prevent:

  • cross-origin timing attacks
  • cross-origin script inclusion
  • CSRF
  • limited privacy protection

The possible values for this flag are lax or strict.


Using this vulnerability, an attacker can:-

  • redirect the user to a malicious site to steal information/data.
  • show user false data which will, in turn, affect the credibility of the website.

Mitigation / Precaution

Beagle recommends setting the flag to lax and strict for maximum security. The ‘strict’ attribute prevents a cookie from being sent by the browser to the target site in all cross-site browsing context. The default ‘lax’ value provides a proper balance between security and usability for websites. This flag is used by applications that maintain a user’s logged-in session.

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