CVE-2021-26321

PSP interruption via insufficient ID command validation

Published Nov 16, 2021 · Updated Sep 16, 2024

Improper input validation in AMD 1st, 2nd, and 3rd Gen EPYC SEV firmware allows local users to interrupt the PSP. The SEV firmware accepts an ID command without sufficient validation; AMD has not disclosed the unchecked field or resulting failure path. Exploitation requires authenticated local access and interrupts the Platform Security Processor, with no reported confidentiality or integrity impact.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in AMD 1st, 2nd, and 3rd Gen EPYC SEV firmware allows local users to interrupt the PSP. The SEV firmware accepts an ID command without sufficient validation; AMD has not disclosed the unchecked field or resulting failure path. Exploitation requires authenticated local access and interrupts the Platform Security Processor, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2021-26321
Published
Nov 16, 2021
Updated
Sep 16, 2024
Vendor
AMD
Product
2nd Gen AMD EPYC Processors
Classifications
CWE-77, CWE-20, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <RomePI-SP3_1.0.0.C

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

AMD · 2nd Gen AMD EPYC Processorsversion=unspecified <RomePI-SP3_1.0.0.C
AMD · 3rd Gen AMD EPYC Processorsversion=unspecified <MilanPI-SP3_1.0.0.4
AMD · 1st Gen AMD EPYC Processorsversion=unspecified <NaplesPI-SP3_1.0.0.G

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
CWE-20Improper Input Validation
T1499.004Application or System Exploitation

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

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Your stack

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