CVE-2023-20520Network attack vector

Arbitrary code execution via return-address corruption

Published May 9, 2023 · Updated Jan 28, 2025

Stack-based buffer overflow in the ASP Bootloader on 1st–3rd Gen AMD EPYC processors allows attackers to execute arbitrary code. The bootloader's improper access-control settings permit corruption of its saved return address, producing a stack overrun. AMD does not disclose the input path or required foothold, so network reachability and the resulting code-execution context remain unspecified.

CVSS severity9.8
Critical
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stack-based buffer overflow in the ASP Bootloader on 1st–3rd Gen AMD EPYC processors allows attackers to execute arbitrary code. The bootloader's improper access-control settings permit corruption of its saved return address, producing a stack overrun. AMD does not disclose the input path or required foothold, so network reachability and the resulting code-execution context remain unspecified.

The record

CVE
CVE-2023-20520
Published
May 9, 2023
Updated
Jan 28, 2025
Vendor
AMD
Product
2nd Gen AMD EPYC Processors
Classifications
CWE-787
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 9, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 28, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=various

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

AMD · 2nd Gen AMD EPYC Processorsversion=various
AMD · 3rd Gen AMD EPYC Processorsversion=various
AMD · 1st Gen AMD EPYC Processorsversion=various

Published CVSS scores

9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo