The Spectre v1 hardware vulnerability is
often characterized as
allowing array bounds checks to be bypassed via speculative execution.
While that is true, it is not the full extent of the shenanigans allowed by
this particular class of vulnerabilities. For a demonstration of that
fact, one need look no further than the “SWAPGS vulnerability” known as
CVE-2019-1125 to the wider world or as “Grand Schemozzle” to the select
group of developers who addressed it in the Linux kernel.

Source: LWN.net – [$] Grand Schemozzle: Spectre continues to haunt