#VU52772 Buffer overflow in Xen - CVE-2020-29568

Vulnerability identifier: #VU52772

Vulnerability risk: Low

CVSSv4.0: 5.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:U/U:Clear]

CVE-ID: CVE-2020-29568

CWE-ID: CWE-119

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Xen
Server applications / Virtualization software

Vendor: Xen Project

Description

The vulnerability allows a local authenticated user to a crash the entire system.

An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are processing watch events using a single thread. If the events are received faster than the thread is able to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Xen: 4.0.0 - 4.15.0

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External links
https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
https://www.debian.org/security/2021/dsa-4843
https://xenbits.xenproject.org/xsa/advisory-349.html

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

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