CVE-2019-18660
The Linux kernel before 5.4.1 on powerpc allows Information Exposure because the Spectre-RSB mitigation is not in place for all applicable CPUs, aka CID-39e72bf96f58. This is related to arch/powerpc/kernel/entry_64.S and arch/powerpc/kernel/security.c.
Date published : 2019-11-27
https://seclists.org/bugtraq/2020/Jan/10
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.1