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Improper Privilege Management Affecting xen package, versions <4.13.0-r0

0.0
critical

Snyk CVSS

    Attack Complexity Low
    Confidentiality High
    Integrity High
    Availability High

    Threat Intelligence

    EPSS 1.37% (87th percentile)
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NVD
9.8 critical
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SUSE
7.8 high

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  • Snyk ID SNYK-ALPINE315-XEN-1929307
  • published 21 Jul 2020
  • disclosed 31 Oct 2019
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Introduced: 31 Oct 2019

CVE-2019-18425 Open this link in a new tab
CWE-269 Open this link in a new tab

How to fix?

Upgrade Alpine:3.15 xen to version 4.13.0-r0 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 Alpine. See How to fix? for Alpine:3.15 relevant fixed versions and status.

An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.

References