The "Hertzbleed" vulnerability [LWN.net]

Today's branded, logo-equipped vulnerability is known as Hertzbleed; it affects x86 processors (at least) and can be exploited in some situations to extract cryptographic keys from a remote server.

Hertzbleed takes advantage of our experiments showing that, under certain circumstances, the dynamic frequency scaling of modern x86 processors depends on the data being processed. This means that, on modern processors, the same program can run at a different CPU frequency (and therefore take a different wall time) when computing, for example, 2022 + 23823 compared to 2022 + 24436.

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