How severe is CVE-2023-20521?

CVE-2023-20521 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over physical access with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.

Is CVE-2023-20521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-20521?

CVE-2023-20521 primarily affects Amd Epyc 7001 Firmware. In total, 93 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-20521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2023-20521 published?

CVE-2023-20521 was published on 2023-11-14 and last updated on 2026-06-17.

CVE-2023-20521

CVE-2023-20521 is a low-severity vulnerability in Amd Epyc 7001 Firmware with a CVSS 3.x base score of 3.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-367.

Key facts

Severity: Low (CVSS 3.x base score 3.3)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-367
Affected product: Amd Epyc 7001 Firmware
Published: 2023-11-14
Last modified: 2026-06-17

Description

TOCTOU in the ASP Bootloader may allow an attacker with physical access to tamper with SPI ROM records after memory content verification, potentially leading to loss of confidentiality or a denial of service.

Frequently asked questions

What is CVE-2023-20521?: TOCTOU in the ASP Bootloader may allow an attacker with physical access to tamper with SPI ROM records after memory content verification, potentially leading to loss of confidentiality or a denial of service.
How severe is CVE-2023-20521?: CVE-2023-20521 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over physical access with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability low.
Is CVE-2023-20521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-20521?: CVE-2023-20521 primarily affects Amd Epyc 7001 Firmware. In total, 93 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-20521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-20521 published?: CVE-2023-20521 was published on 2023-11-14 and last updated on 2026-06-17.

References

Affected products (93)

cpe:2.3:o:amd:epyc_7001_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7251_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7261_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7281_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7301_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7351_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7351p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7371_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7401_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7401p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7451_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7501_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7551_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7551p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7601_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7232p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7252_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7262_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7272_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7282_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7302_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7302p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7352_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7402_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7402p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7452_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7502_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7502p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7532_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7542_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7552_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7642_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7662_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7702_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7702p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7742_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7f32_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7f52_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7f72_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7h12_firmware:*:*:*:*:*:*:*:*

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