SB2020121536 - Input validation error in Xen

Description

This security bulletin contains information about 1 security vulnerability.

1) Input validation error (CVE-ID: CVE-2020-29481)

The vulnerability allows a local authenticated user to execute arbitrary code.

An issue was discovered in Xen through 4.14.x. Access rights of Xenstore nodes are per domid. Unfortunately, existing granted access rights are not removed when a domain is being destroyed. This means that a new domain created with the same domid will inherit the access rights to Xenstore nodes from the previous domain(s) with the same domid. Because all Xenstore entries of a guest below /local/domain/<domid> are being deleted by Xen tools when a guest is destroyed, only Xenstore entries of other guests still running are affected. For example, a newly created guest domain might be able to read sensitive information that had belonged to a previously existing guest domain. Both Xenstore implementations (C and Ocaml) are vulnerable.

Remediation

Install update from vendor's website.

References

• http://www.openwall.com/lists/oss-security/2020/12/16/3
• https://www.debian.org/security/2020/dsa-4812
• https://xenbits.xenproject.org/xsa/advisory-322.html