最近我碰到个棘手的问题——不管用Firefox还是Chrome浏览器，都没法正常打开https://web.telegram.org/，而且不止这一个网站，最近几天里https://rauias.com/、https://www.amazon.in/、https://byjus.com/等一大批网站都弹出了同样的安全证书警告，完全没法正常访问。

先说说Chrome上的具体报错：

Your connection is not private
Attackers might be trying to steal your information from web.telegram.org (for example, passwords, messages, or credit cards).
Learn more
NET::ERR_CERT_AUTHORITY_INVALID
Subject: web.telegram.org
Issuer: Cisco Umbrella Secondary SubCA fra-SG
Expires on: Nov 27, 2023
Current date: Nov 25, 2023

再看看Firefox给出的提示：

Warning: Potential Security Risk Ahead
Firefox detected a potential security threat and did not continue to web.telegram.org. If you visit this site, attackers could try to steal information like your passwords, emails, or credit card details.

What can you do about it?
The issue is most likely with the web site, and there is nothing you can do to resolve it.
If you are on a corporate network or using anti-virus software, you can reach out to the support teams for assistance. You can also notify the web site’s administrator about the problem.

我已经尝试了一些办法：昨天刚完成了系统的全量更新和升级（我平时基本每天都会更新一次），也重启过电脑了，但问题还是没有解决。有没有大佬能帮我分析下这到底是哪里出了问题，该怎么解决呢？

备注：内容来源于stack exchange，提问作者Carson Nicholson