Denial of service in Linux kernel

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU55262

Risk: Low

CVSSv3.1: 4.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-36311

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a local user to perform a denial of service attack.

The vulnerability exists due to an error in arch/x86/kvm/svm/sev.c in Linux kernel, which allows soft lockup by triggering destruction of a large SEV VM (which requires unregistering many encrypted regions).

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.9.0

External links

http://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.9
http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7be74942f184fdfba34ddd19a0d995deb34d4a03
http://lists.debian.org/debian-lts-announce/2021/07/msg00015.html

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.