Incorrect Permission Assignment for Critical Resource Affecting xen package, versions <4.11.4+57-g41a822c392-2


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.05% (16th percentile)

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  • Snyk IDSNYK-DEBIAN10-XEN-1051738
  • published16 Dec 2020
  • disclosed15 Dec 2020

Introduced: 15 Dec 2020

CVE-2020-29479  (opens in a new tab)
CWE-732  (opens in a new tab)

How to fix?

Upgrade Debian:10 xen to version 4.11.4+57-g41a822c392-2 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. In the Ocaml xenstored implementation, the internal representation of the tree has special cases for the root node, because this node has no parent. Unfortunately, permissions were not checked for certain operations on the root node. Unprivileged guests can get and modify permissions, list, and delete the root node. (Deleting the whole xenstore tree is a host-wide denial of service.) Achieving xenstore write access is also possible. All systems using oxenstored are vulnerable. Building and using oxenstored is the default in the upstream Xen distribution, if the Ocaml compiler is available. Systems using C xenstored are not vulnerable.

CVSS Scores

version 3.1