Bug 1905668 (CVE-2020-29479) - CVE-2020-29479 xen: oxenstored: permissions not checked on root node (XSA-353)
Summary: CVE-2020-29479 xen: oxenstored: permissions not checked on root node (XSA-353)
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2020-29479
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1908002
Blocks: 1903644
TreeView+ depends on / blocked
 
Reported: 2020-12-08 19:18 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-02-16 18:45 UTC (History)
4 users (show)

Fixed In Version:
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Environment:
Last Closed: 2020-12-15 22:20:04 UTC


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Description Guilherme de Almeida Suckevicz 2020-12-08 19:18:42 UTC
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 hostwide denial
of service.  Depending on the circumstances, the vulnerability can
also be leveraged into an ability to gain write access to any part of
xenstore.

Comment 1 Guilherme de Almeida Suckevicz 2020-12-15 16:28:21 UTC
External References:

https://www.openwall.com/lists/oss-security/2020/12/15/13

Comment 2 Guilherme de Almeida Suckevicz 2020-12-15 16:28:46 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1908002]

Comment 3 Product Security DevOps Team 2020-12-15 22:20:04 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.


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