Fix it in your stack

Tested fixes for CWE-1275 in Express, Flask, Spring Boot, ASP.NET Core, Rails and Laravel: the vulnerable code, the fix, a plausible fix that still fails, and the regression tests.

Definition

MITRE’s description of CWE-1275: The SameSite attribute for sensitive cookies is not set, or an insecure value is used.

Common consequences MITRE lists

  • Confidentiality, Integrity, Non-Repudiation, Access Control: Modify Application Data

Why it matters

Cookies sent with cross-site requests make CSRF and some cross-site data leaks possible.

How to prevent it

  • Set SameSite=Lax or Strict explicitly on session cookies; use None only for flows that need it, and then with Secure.
  • Keep CSRF defenses such as Origin or Sec-Fetch-Site checks, because SameSite does not stop same-site attackers.

Guides on this site

Also covers this · Guide

Protect cookie-authenticated actions against CSRF

Make the server distinguish an intended action from a request another site caused the browser to send.

Also covers this · Guide

Session management: cookies, timeouts, rotation and revocation

Model authentication as transitions in server authority, set session cookies and timeouts to current NIST and OWASP values, and verify fixation prevention, expiry, reauthentication, revocation and stolen-cookie defenses.

Practice

References

  1. CWE-1275 in the MITRE CWE list (version 4.20)

List data from MITRE; the name, definition and consequences are from MITRE’s CWE 4.20 catalogue. A guide is listed as the main subject when the weakness is what the guide is about, and as covering it when a dedicated section or worked example addresses it.

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