Skip to content
Fencer Vulns
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 2023-05-09 3 y ago modified 2026-06-17 4 mo 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
21 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

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 Vulns 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.