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CVE-2020-29479

Published: 15 December 2020

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.

Notes

AuthorNote
mdeslaur
hypervisor packages are in universe. For
issues in the hypervisor, add appropriate
tags to each section, ex:
Tags_xen: universe-binary

Priority

Medium

Cvss 3 Severity Score

8.8

Score breakdown

Status

Package Release Status
xen
Launchpad, Ubuntu, Debian
trusty Does not exist

upstream Needs triage

bionic Needed

focal Needed

groovy Ignored
(end of life)
jammy Not vulnerable
(4.11.4+57-g41a822c392-2)
xenial Needed

impish Ignored
(end of life)
hirsute Ignored
(end of life)
kinetic Not vulnerable
(4.11.4+57-g41a822c392-2)
lunar Not vulnerable
(4.11.4+57-g41a822c392-2)
mantic Not vulnerable
(4.11.4+57-g41a822c392-2)
Binaries built from this source package are in Universe and so are supported by the community.

Severity score breakdown

Parameter Value
Base score 8.8
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H