--- title: "Vulnerability Knowledge Base | Pop SS\n | Ubuntu" description: Kernel Exception Handling Flaws After MOV/POP to SS Instructions (CVE-2018-8897, CVE-2018-1087) url: https://ubuntu.com/security/vulnerabilities/pop-ss?format=md keywords: index, follow --- 1. [Vulnerability knowledge base](https://ubuntu.com/security/vulnerabilities) 2. [View all](https://ubuntu.com/security/vulnerabilities/view-all) 3. Pop SS --- # Pop SS Kernel Exception Handling Flaws After MOV/POP to SS Instructions (CVE-2018-8897, CVE-2018-1087) Published 8 May 2018 Updated 1 year, 6 months ago --- Open side navigation Nick Peterson discovered that the Linux kernel did not properly handle debug exceptions following a MOV/POP to SS instruction. A local attacker could use this to cause a denial of service (system crash). This issue only affected the amd64 architecture. ([CVE-2018-8897](https://ubuntu.com/security/CVE-2018-8897)) Andy Lutomirski discovered that the KVM subsystem of the Linux kernel did not properly emulate the ICEBP instruction following a MOV/POP to SS instruction. A local attacker in a KVM virtual machine could use this to cause a denial of service (guest VM crash) or possibly escalate privileges inside of the virtual machine. This issue only affected the i386 and amd64 architectures. ([CVE-2018-1087](https://ubuntu.com/security/CVE-2018-1087)) These issues were fixed in the Linux kernel by commits [`x86/entry/64: Don't use IST entry for #BP stack`](https://git.kernel.org/linus/d8ba61ba58c88d5207c1ba2f7d9a2280e7d03be9) and [`kvm/x86: fix icebp instruction handling`](https://git.kernel.org/linus/32d43cd391bacb5f0814c2624399a5dad3501d09). Ubuntu 17.10, 16.04 LTS, 14.04 LTS, and 12.04 ESM were affected. To address the issues, the majority of users should ensure that linux-`image-4.13.0-41-generic` `4.13.0-41.46` (Ubuntu 17.10), `linux-image-4.4.0-124-generic` `4.4.0-124.148` (Ubuntu 16.04 LTS), `linux-image-3.13.0-147-generic` `3.13.0-147.196` (Ubuntu 14.04 LTS), or `linux-image-3.2.0-134-generic` `3.2.0-134.180` (Ubuntu 12.04 ESM) is installed. Users of non-generic Ubuntu kernels should consult the published Ubuntu Security Notices for version information. These updates were announced in [USN 3641-1](https://ubuntu.com/security/notices/USN-3641-2) (Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 17.10) and [USN 3641-2](https://ubuntu.com/security/notices/USN-3641-2) (Ubuntu 12.04 ESM). --- ## Timeline * 2018 May 08: the issue is made public on the agreed upon coordinated release date * 2018 May 08: USNs [3641-1](https://ubuntu.com/security/notices/USN-3641-1) and [3641-2](https://ubuntu.com/security/notices/USN-3641-2) are published