CVE-2021-26391

Privileged code execution via unchecked header signatures

Published Nov 9, 2022 · Updated May 1, 2025

Improper signature verification in AMD graphics firmware allows local users with privileges to execute code in a Trusted Application or OS kernel. The Trusted Application loader does not adequately verify multiple header signatures before loading the application. Prior privileged local access is required; successful exploitation grants code execution inside the Trusted Application or host OS/kernel.

CVSS severity7.8
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in AMD graphics firmware allows local users with privileges to execute code in a Trusted Application or OS kernel. The Trusted Application loader does not adequately verify multiple header signatures before loading the application. Prior privileged local access is required; successful exploitation grants code execution inside the Trusted Application or host OS/kernel.

The record

CVE
CVE-2021-26391
Published
Nov 9, 2022
Updated
May 1, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 9, 2022CVE publishedPublication date reported by the CVE source.
  2. May 1, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1068Exploitation for Privilege Escalation

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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