kernel KVM before versions kernel 4.16, kernel 4.16-rc7, kernel 4.17-rc1, kernel 4.17-rc2 and kernel 4.17-rc3 is vulnerable to a flaw in the way the Linux kernel's KVM hypervisor handled exceptions delivered after a stack switch operation via Mov SS or Pop SS instructions. During the stack switch operation, the processor did not deliver interrupts and exceptions, rather they are delivered once the first instruction after the stack switch is executed. An unprivileged KVM guest user could use this flaw to crash the guest or, potentially, escalate their privileges in the guest.
http://www.openwall.com/lists/oss-security/2018/05/08/5
http://www.securityfocus.com/bid/104127
http://www.securitytracker.com/id/1040862
https://access.redhat.com/errata/RHSA-2018:1318
https://access.redhat.com/errata/RHSA-2018:1345
https://access.redhat.com/errata/RHSA-2018:1347
https://access.redhat.com/errata/RHSA-2018:1348
https://access.redhat.com/errata/RHSA-2018:1355
https://access.redhat.com/errata/RHSA-2018:1524
https://access.redhat.com/security/vulnerabilities/pop_ss
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2018-1087
https://usn.ubuntu.com/3641-1/
Source: MITRE
Published: 2018-05-15
Updated: 2019-10-09
Type: NVD-CWE-noinfo
Base Score: 4.6
Vector: AV:L/AC:L/Au:N/C:P/I:P/A:P
Impact Score: 6.4
Exploitability Score: 3.9
Severity: MEDIUM
Base Score: 7.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 1.8
Severity: HIGH