Earlier this month, a security researcher discovered that private cryptographic keys associated with eight of Indian company eMudhra's intermediate certificate authority (CA) certificates were weak. The compromised keys could have allowed attackers to impersonate legitimate websites, potentially putting users' sensitive information at risk. However, there is currently no evidence that the keys were exploited maliciously.

eMudhra's certificates were widely trusted by all major web browsers, including Safari, Chrome, Edge, and Firefox, but Apple and the other companies behind those browsers have since taken action to protect users.

In a support document, Apple said it has been blocking eMudhra's compromised TLS web certificates since October 19 in Safari, Mail, and apps that use Apple's networking and security frameworks. The certificates are blocked automatically with no software update required, so most Apple device owners do not need to take any action.

There is one exception. Apple said those who use macOS command-line tools, such as system administrators, should be aware that some of those tools can still accept the compromised certificates until Apple releases a macOS update with a fix. In the meantime, Apple said those who use command-line tools can remove root CA certificates from the /etc/ssl/cert.pem file.

Apple has not provided a release date for the macOS update that will include the necessary changes to the /etc/ssl/cert.pem file by default.

For more technical details, read Apple's support document.