CVE-2020-25596

 

Published at: - 24-09-2020 12:15

Last modified: - 21-11-2022 03:24

Total changes: - 2

Description

An issue was discovered in Xen through 4.14.x. x86 PV guest kernels can experience denial of service via SYSENTER. The SYSENTER instruction leaves various state sanitization activities to software. One of Xen's sanitization paths injects a #GP fault, and incorrectly delivers it twice to the guest. This causes the guest kernel to observe a kernel-privilege #GP fault (typically fatal) rather than a user-privilege #GP fault (usually converted into SIGSEGV/etc.). Malicious or buggy userspace can crash the guest kernel, resulting in a VM Denial of Service. All versions of Xen from 3.2 onwards are vulnerable. Only x86 systems are vulnerable. ARM platforms are not vulnerable. Only x86 systems that support the SYSENTER instruction in 64bit mode are vulnerable. This is believed to be Intel, Centaur, and Shanghai CPUs. AMD and Hygon CPUs are not believed to be vulnerable. Only x86 PV guests can exploit the vulnerability. x86 PVH / HVM guests cannot exploit the vulnerability.

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

 

Verification logic

 

Reference

• https://xenbits.xen.org/xsa/advisory-339.html
• FEDORA-2020-306b84fd07-Third Party Advisory
• FEDORA-2020-f668e579be-Third Party Advisory
• DSA-4769-Third Party Advisory
• openSUSE-SU-2020:1608-Third Party Advisory
• FEDORA-2020-d46fe34349-Mailing List, Third Party Advisory
• GLSA-202011-06-Third Party Advisory

 

Keywords

NVD

 

CVE-2020-25596

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures