CVE-2021-26315Public exploit

PSP code execution via unchecked firmware decryption

Published Nov 16, 2021 · Updated Sep 17, 2024

Firmware integrity verification in 3rd Gen AMD EPYC processors before MilanPI-SP3_1.0.0.4 allows local users to execute PSP code. The PSP boot ROM authenticates an encrypted off-chip firmware image, then decrypts it without adequately verifying the decrypted image's integrity. Physical access or high privileges are required to modify the firmware input; exploitation compromises PSP code execution and attestation authenticity.

CVSS severity7.8
High
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Firmware integrity verification in 3rd Gen AMD EPYC processors before MilanPI-SP3_1.0.0.4 allows local users to execute PSP code. The PSP boot ROM authenticates an encrypted off-chip firmware image, then decrypts it without adequately verifying the decrypted image's integrity. Physical access or high privileges are required to modify the firmware input; exploitation compromises PSP code execution and attestation authenticity.

The record

CVE
CVE-2021-26315
Published
Nov 16, 2021
Updated
Sep 17, 2024
Vendor
Advanced Micro Devices, Inc.
Product
3rd Gen AMD EPYC Processors
Classifications
CWE-345, T1542.001
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Nov 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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 <MilanPI-SP3_1.0.0.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Advanced Micro Devices, Inc. · 3rd Gen AMD EPYC Processorsversion=unspecified <MilanPI-SP3_1.0.0.4

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1542.001System Firmware

Public exploit references

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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