#VU63684 Input validation error in 3rd Gen AMD EPYC Processors - CVE-2021-26339

Vulnerability identifier: #VU63684

Vulnerability risk: Medium

CVSSv4.0: 4.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-26339

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
3rd Gen AMD EPYC Processors
Hardware solutions / Firmware

Vendor: AMD

Description

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

The vulnerability exists due to an error in the AMD CPU’s core logic when using specific code from an unprivileged VM. A remote user with low-privileged access to guest OS can send a specific x86 instruction sequence that triggers CPU core hang.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

3rd Gen AMD EPYC Processors: before MilanPI-SP3_1.0.0.7

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External links
https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1028

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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 Internet.

Is there known malware, which exploits this vulnerability?

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