Arbitrary Code Injection Affecting xen package, versions <4.11.4+37-g3263f257ca-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.05% (16th percentile)

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  • Snyk IDSNYK-DEBIAN10-XEN-1011846
  • published23 Sept 2020
  • disclosed23 Sept 2020

Introduced: 23 Sep 2020

CVE-2020-25596  (opens in a new tab)
CWE-74  (opens in a new tab)

How to fix?

Upgrade Debian:10 xen to version 4.11.4+37-g3263f257ca-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Debian. See How to fix? for Debian:10 relevant fixed versions and status.

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.

CVSS Scores

version 3.1