#VU31980 Resource management error in Xen - CVE-2019-19581

Vulnerability identifier: #VU31980

Vulnerability risk: Medium

CVSSv4.0: 5.6 [CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:U/U:Green]

CVE-ID: CVE-2019-19581

CWE-ID: CWE-399

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
Xen
Server applications / Virtualization software

Vendor: Xen Project

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

An issue was discovered in Xen through 4.12.x allowing 32-bit Arm guest OS users to cause a denial of service (out-of-bounds access) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On 32-bit Arm accesses to bitmaps with bit a count which is a multiple of 32, an out of bounds access may occur. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. 32-bit Arm systems are vulnerable. 64-bit Arm systems are not vulnerable.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Xen: 4.8.0 - 4.12.1

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External links
https://lists.opensuse.org/opensuse-security-announce/2020-01/msg00011.html
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/34HBFTYNMQMWIO2GGK7DB6KV4M6R5YPV/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D5R73AYE53QA32KTMHUVKCX6E52CIS43/
https://seclists.org/bugtraq/2020/Jan/21
https://security.gentoo.org/glsa/202003-56
https://www.debian.org/security/2020/dsa-4602
https://xenbits.xen.org/xsa/advisory-307.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.