CVE-2021-26356

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read...

7.4 High

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and information disclosure.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: None

Exploit likelihood

0.40%Up 0.4 points since May 10, 2023

What each source reports

NVD Score used 7.4

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and information disclosure.

Record: CVE-2021-26356
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness: CWE-367
Updated: 2026-11-02

CVE List 7.4

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and information disclosure.

Record: CVE-2021-26356
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness: CWE-367
Updated: 2026-11-02

EUVDEUVD-2021-13162 7.4

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and information disclosure.

Record: EUVD-2021-13162
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Updated: 2026-11-03

GitHub AdvisoriesGHSA-8c2m-2hmv-32px 7.4

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read...

A TOCTOU in ASP bootloader may allow an attacker to tamper with the SPI ROM following data read to memory potentially resulting in S3 data corruption and information disclosure.

Record: GHSA-8c2m-2hmv-32px
CVSS 3.1: 7.4 HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness: CWE-367
Updated: 2026-11-02

Affected products

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History

History
Recorded	Changed	Sources
Nov 3, 2026	aliases, published	EUVD
Nov 2, 2026	first indexed	CVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-26356 is a high vulnerability (CVSS 7.4) in Amd 1st Gen Amd Epyc™ Processors, published May 9, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. No source names a fixed version.

Attack profile

How easy it is to exploit

What an attacker can affect

Exploit likelihood

What each source reports

Affected products

History

In short

References