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.
http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00029.html
http://www.openwall.com/lists/oss-security/2019/11/27/1
https://access.redhat.com/errata/RHSA-2020:0174
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.1
https://seclists.org/bugtraq/2020/Jan/10
https://security.netapp.com/advisory/ntap-20200103-0001/
https://usn.ubuntu.com/4225-1/
https://usn.ubuntu.com/4225-2/
https://usn.ubuntu.com/4226-1/
https://usn.ubuntu.com/4227-1/
https://usn.ubuntu.com/4227-2/
https://usn.ubuntu.com/4228-1/
Source: MITRE
Published: 2019-11-27
Updated: 2020-01-28
Type: CWE-200
Base Score: 1.9
Vector: AV:L/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 3.4
Severity: LOW
Base Score: 4.7
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 1
Severity: MEDIUM