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CVE-2017-10920: Xen: Memory corruption

CVE-2017-10920 is rated critical with a CVSS v3.0 base score of 10.0 and affects Xen. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

The grant-table feature in Xen through 4.8.x mishandles a GNTMAP_device_map and GNTMAP_host_map mapping, when followed by only a GNTMAP_host_map unmapping, which allows guest OS users to cause a denial of service (count mismanagement and memory corruption) or obtain privileged host OS access, aka XSA-224 bug 1.

Severity breakdown

CVSS v3.0 10.0: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

Affected products

• Xen: up to and including 4.8.1

References

• https://xenbits.xen.org/xsa/advisory-224.html
• http://www.debian.org/security/2017/dsa-3969
• http://www.securitytracker.com/id/1038734
• https://security.gentoo.org/glsa/201708-03
• https://security.gentoo.org/glsa/201710-17