Timing Attack Vulnerability in macOS 10.14.5 with Hyperthreading Enabled

CVE-2019-9815 · MEDIUM Severity

AV:N/AC:M/AU:N/C:P/I:P/A:P

If hyperthreading is not disabled, a timing attack vulnerability exists, similar to previous Spectre attacks. Apple has shipped macOS 10.14.5 with an option to disable hyperthreading in applications running untrusted code in a thread through a new sysctl. Firefox now makes use of it on the main thread and any worker threads. *Note: users need to update to macOS 10.14.5 in order to take advantage of this change.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

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