Google security researchers have improved the Retbleed CPU side-channel attack to increase exfiltration speed.
The attack can now leak data at 13 KB/s, which is fast enough to be used in modern cloud environments.

Blog: Exploiting Retbleed in the real world
Curious to hear about our experience exploiting Retbleed (a security vulnerability affecting modern CPUs)? Then check out this post to see how we pushed the boundaries of Retbleed exploitation and understand more about the security implications of this exploit for modern computing systems.
(bughunters.google.com)