A backporting error was discovered in the Linux stable/longterm kernel 4.4.x through 4.4.190, 4.9.x through 4.9.190, 4.14.x through 4.14.141, 4.19.x through 4.19.69, and 5.2.x through 5.2.11. Misuse of the upstream "x86/ptrace: Fix possible spectre-v1 in ptrace_get_debugreg()" commit reintroduced the Spectre vulnerability that it aimed to eliminate. This occurred because the backport process depends on cherry picking specific commits, and because two (correctly ordered) code lines were swapped.
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00064.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00066.html
https://grsecurity.net/teardown_of_a_failed_linux_lts_spectre_fix.php
https://lists.debian.org/debian-lts-announce/2019/10/msg00000.html
https://seclists.org/bugtraq/2019/Sep/41
https://security.netapp.com/advisory/ntap-20191004-0001/
https://usn.ubuntu.com/4157-1/
https://usn.ubuntu.com/4157-2/
https://usn.ubuntu.com/4162-1/
https://usn.ubuntu.com/4162-2/
https://usn.ubuntu.com/4163-1/
Source: MITRE
Published: 2019-09-04
Updated: 2019-10-17
Type: CWE-200
Base Score: 4.7
Vector: AV:L/AC:M/Au:N/C:C/I:N/A:N
Impact Score: 6.9
Exploitability Score: 3.4
Severity: MEDIUM
Base Score: 5.6
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
Impact Score: 4
Exploitability Score: 1.1
Severity: MEDIUM