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CVE-2021-26356

23
FAUCET Score

CVE-2021-26356 is a Time-of-Check to Time-of-Use (TOCTOU) vulnerability in the AMD ASP bootloader, allowing an attacker to tamper with SPI ROM data after it's read into memory. This could lead to S3 data corruption and information disclosure. With a CVSS score of 7.4 (HIGH), it presents a high impact on confidentiality and integrity, though it requires high attack complexity. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< naplespi_1.0.0.hCPE matchmatch criteria
cpe:2.3:o:amd:epyc_7001_firmware:*:*:*:*:*:*:*:*
< naplespi_1.0.0.hCPE matchmatch criteria
cpe:2.3:o:amd:epyc_7251_firmware:*:*:*:*:*:*:*:*
< naplespi_1.0.0.hCPE matchmatch criteria
cpe:2.3:o:amd:epyc_7261_firmware:*:*:*:*:*:*:*:*
< naplespi_1.0.0.hCPE matchmatch criteria
cpe:2.3:o:amd:epyc_7281_firmware:*:*:*:*:*:*:*:*
< naplespi_1.0.0.hCPE matchmatch criteria
cpe:2.3:o:amd:epyc_7301_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.4HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
5.2
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.40%
Probability of exploitation in next 30 days
EPSS Percentile
32.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0040 is in the 7th percentile among its peer group of 8,920 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

amd.com / en/corporate/product-security/bulletin/AMD-SB-3001
Vendor Advisory
amd.com / en/corporate/product-security/bulletin/AMD-SB-4001
Vendor Advisory