CVE-2020-25596

MEDIUM
New! CVE Severity Now Using CVSS v3

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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.

References

http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00008.html

https://lists.fedoraproject.org/archives/list/[email protected]oject.org/message/4JRXMKEMQRQYWYEPHVBIWUEAVQ3LU4FN/

https://lists.fedoraproject.org/archives/list/[email protected]/message/DA633Y3G5KX7MKRN4PFEGM3IVTJMBEOM/

https://lists.fedoraproject.org/archives/list/[email protected]/message/RJZERRBJN6E6STDCHT4JHP4MI6TKBCJE/

https://security.gentoo.org/glsa/202011-06

https://www.debian.org/security/2020/dsa-4769

https://xenbits.xen.org/xsa/advisory-339.html

Details

Source: MITRE

Published: 2020-09-23

Updated: 2020-11-11

Type: CWE-74

Risk Information

CVSS v2

Base Score: 2.1

Vector: AV:L/AC:L/Au:N/C:N/I:N/A:P

Impact Score: 2.9

Exploitability Score: 3.9

Severity: LOW

CVSS v3

Base Score: 5.5

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

Impact Score: 3.6

Exploitability Score: 1.8

Severity: MEDIUM

Tenable Plugins

View all (14 total)

IDNameProductFamilySeverity
150542SUSE SLES11 Security Update : xen (SUSE-SU-2020:14521-1)NessusSuSE Local Security Checks
medium
143873SUSE SLES12 Security Update : xen (SUSE-SU-2020:2787-1)NessusSuSE Local Security Checks
medium
143853SUSE SLES12 Security Update : xen (SUSE-SU-2020:2788-1)NessusSuSE Local Security Checks
medium
143805SUSE SLES12 Security Update : xen (SUSE-SU-2020:2822-1)NessusSuSE Local Security Checks
medium
143707SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2020:2791-1)NessusSuSE Local Security Checks
medium
143685SUSE SLES12 Security Update : xen (SUSE-SU-2020:2786-1)NessusSuSE Local Security Checks
medium
143637SUSE SLED15 / SLES15 Security Update : xen (SUSE-SU-2020:2790-1)NessusSuSE Local Security Checks
medium
142854GLSA-202011-06 : Xen: Multiple vulnerabilitiesNessusGentoo Local Security Checks
high
141501Xen x86 PV guest kernels DoS (XSA-339)NessusMisc.
medium
141278Fedora 31 : xen (2020-d46fe34349)NessusFedora Local Security Checks
medium
141270Fedora 33 : xen (2020-306b84fd07)NessusFedora Local Security Checks
medium
141168openSUSE Security Update : xen (openSUSE-2020-1608)NessusSuSE Local Security Checks
medium
141138Debian DSA-4769-1 : xen - security updateNessusDebian Local Security Checks
medium
141102Fedora 32 : xen (2020-f668e579be)NessusFedora Local Security Checks
medium