#VU22541 Input validation error in Xen - CVE-2019-18420

Vulnerability identifier: #VU22541

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-2019-18420

CWE-ID: CWE-20

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.

The vulnerability exists due to insufficient validation of user-supplied input within the VCPUOP_initialise hypercall in Xen. A remote user on a guest operating system can run a specially crafted program and perform a denial of service attack against the host operating system.

Mitigation

xsa296.patch           Xen 4.9 ... unstable
xsa296-4.8.patch       Xen 4.7 ... 4.8

$ sha256sum xsa296*
71bd433f788dd511fad90165bc5ba9bcabe949eecd912f2a616e3c996960d67d  xsa296.meta
ccfd81b162b8535d952f56b1f87dfdd960e71bf07c1cf8388976e78e2e86cde5  xsa296.patch
b283be3df6789402553172b7fd582bfffb4fa72a6b33543439bd2fb1b87bfbd4  xsa296-4.8.patch
$

Vulnerable software versions

Xen: 4.6.0 - 4.9.4

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External links
https://www.openwall.com/lists/oss-security/2019/10/31/1
https://xenbits.xen.org/xsa/advisory-296.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.