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Fencer Intel
high 7.4

CVE-2021-26356 json

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…

published 3y ago modified 4mo ago also EUVD-2021-13162

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

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.

Patch / fix

  • amd epyc_7001_firmware naplespi_1.0.0.h
  • amd epyc_7251_firmware naplespi_1.0.0.h
  • amd epyc_7261_firmware naplespi_1.0.0.h
  • amd epyc_7281_firmware naplespi_1.0.0.h
  • amd epyc_7301_firmware naplespi_1.0.0.h
  • amd epyc_7351_firmware naplespi_1.0.0.h
  • amd epyc_7351p_firmware naplespi_1.0.0.h
  • amd epyc_7371_firmware naplespi_1.0.0.h
  • amd epyc_7401_firmware naplespi_1.0.0.h
  • amd epyc_7401p_firmware naplespi_1.0.0.h
  • amd epyc_7451_firmware naplespi_1.0.0.h
  • amd epyc_7501_firmware naplespi_1.0.0.h
  • amd epyc_7551_firmware naplespi_1.0.0.h
  • amd epyc_7551p_firmware naplespi_1.0.0.h
  • amd epyc_7601_firmware naplespi_1.0.0.h
  • amd epyc_7002_firmware romepi_1.0.0.d
  • amd epyc_7232p_firmware romepi_1.0.0.d
  • amd epyc_7252_firmware romepi_1.0.0.d
  • amd epyc_7262_firmware romepi_1.0.0.d
  • amd epyc_7272_firmware romepi_1.0.0.d

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
last yr.

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CNA 3.1 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • AMD Ryzen™ 3000 Series Desktop Processors “Matisse” AM4
  • AMD AMD Ryzen™ 5000 Series Desktop Processors “Vermeer” AM4
  • AMD 3rd Gen AMD Ryzen™ Threadripper™ Processors “Castle Peak” HEDT
  • AMD Ryzen™ Threadripper™ PRO Processors “Castle Peak” WS
  • AMD Ryzen™ Threadripper™ PRO Processors “Chagall” WS
  • AMD 1st Gen AMD EPYC™ Processors
  • AMD 2nd Gen AMD EPYC™ Processors
  • AMD 3rd Gen AMD EPYC™ Processors

Classification

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

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.