CVE-2021-26356

HIGHNVD 7.47.4—

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.

CVSS v3: 7.4
EG Score: 7.4(medium)
EPSS: 50.7%
KEV: Not listed

Published

May 9, 2023

Last Modified

January 28, 2025

References (4)

psirt@amdhttps://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3001
psirt@amdhttps://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-4001
af854a3a-2127-422b-91ae-364da2661108https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3001
af854a3a-2127-422b-91ae-364da2661108https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-4001

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition

Data Freshness Timeline

(refreshed 11× in last 7d / 18× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-25 01:32 UTCEG score recompute
2026-05-25 01:32 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2021-26356?

CVE-2021-26356 is a high vulnerability published on May 9, 2023. 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.

When was CVE-2021-26356 disclosed?

CVE-2021-26356 was first published in the National Vulnerability Database on May 9, 2023, with the most recent update on January 28, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-26356 actively exploited?

CVE-2021-26356 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 50.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-26356?

CVE-2021-26356 has a CVSS v3 base score of 7.4 (NVD).

How do I remediate CVE-2021-26356?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-26356, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-26356

Explore →

Is Your Infrastructure Affected by CVE-2021-26356?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2021-26356

📅 Published

🔄 Last Modified

🔗 References (4)