Because a cookie’s SameSite attribute was not set or is invalid, it defaults to SameSite=Lax, which prevents the cookie from being sent in a cross-site request. This behavior protects user data from accidentally leaking to third parties and cross-site request forgery.

你已经问过这个问题了，我已经给出了回答。同源策略是浏览器的一种安全机制，SameSite属性是一种Cookie属性，用于限制Cookie在跨站点请求中的发送行为，以防止跨站点请求攻击和数据泄漏。如果SameSite属性未设置或设置无效，则默认为SameSite=Lax，这将阻止Cookie在跨站点请求中发送。这种行为保护用户数据不被意外泄漏给第三方和跨站请求伪造。

相关问题

This Set-Cookie header didn't specify a "SameSite" attribute and was defaulted to "SameSite=Lax," and was blocked because it come from a cross-site response which was not the response to a top-level navigation. The Set-Cookie had to have been set with "SameSite=None" to enable cross-site usage.怎么解决这个错误

要解决这个错误，需要在Set-Cookie响应头中添加"SameSite=None"属性，以便启用跨站使用。可以通过以下方式解决该错误：

1. 在服务器端配置Set-Cookie响应头时，添加"SameSite=None"属性。
2. 如果使用的是第三方库或框架，可以查阅其文档，了解如何在响应头中添加"SameSite=None"属性。
3. 如果使用的是浏览器扩展程序，可以在扩展程序中设置"SameSite=None"属性。
4. 如果是在自己的网站上遇到了这个问题，可以在代码中手动添加"SameSite=None"属性，例如：

response.headers['Set-Cookie'] = 'cookie_name=cookie_value; SameSite=None; Secure'

需要注意的是，添加"SameSite=None"属性后，建议同时添加"Secure"属性，以确保安全性。

Indicate whether to send a cookie in a cross-site request by specifying its SameSite attribute

Yes, you can indicate whether to send a cookie in a cross-site request by specifying its SameSite attribute. The SameSite attribute can have three values: "Strict", "Lax", or "None".

- "Strict" means that the cookie should only be sent in a first-party context, meaning that it should only be sent with requests originating from the same site that set the cookie.
- "Lax" is a less strict version of "Strict" that allows some exceptions, such as when a user follows a link from an external site.
- "None" means that the cookie can be sent in any context, including cross-site requests.

Setting the SameSite attribute to "Strict" or "Lax" can help prevent certain types of attacks, such as cross-site request forgery (CSRF). However, it's important to note that not all browsers support the SameSite attribute, so it should be used in conjunction with other security measures.