How severe is CVE-2021-26355?

CVE-2021-26355 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-26355 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26355?

CVE-2021-26355 primarily affects Amd Epyc 7003 Firmware. In total, 24 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26355?

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

When was CVE-2021-26355 published?

CVE-2021-26355 was published on 2023-01-11 and last updated on 2026-06-17.

CVE-2021-26355

CVE-2021-26355 is a medium-severity vulnerability in Amd Epyc 7003 Firmware with a CVSS 3.x base score of 5.5. 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-693.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-693
Affected product: Amd Epyc 7003 Firmware
Published: 2023-01-11
Last modified: 2026-06-17

Description

Insufficient fencing and checks in System Management Unit (SMU) may result in access to invalid message port registers that could result in a potential denial-of-service.

Frequently asked questions

What is CVE-2021-26355?: Insufficient fencing and checks in System Management Unit (SMU) may result in access to invalid message port registers that could result in a potential denial-of-service.
How severe is CVE-2021-26355?: CVE-2021-26355 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-26355 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26355?: CVE-2021-26355 primarily affects Amd Epyc 7003 Firmware. In total, 24 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26355?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-26355 published?: CVE-2021-26355 was published on 2023-01-11 and last updated on 2026-06-17.

References

https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-1032

Affected products (24)

cpe:2.3:o:amd:epyc_7003_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_72f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7313_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7313p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7343_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7373x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_73f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7413_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7443_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7443p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7453_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_74f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7513_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7573x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_75f3_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7643_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7663_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713p_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7743_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7763_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7773x_firmware:*:*:*:*:*:*:*:*

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