How severe is CVE-2021-26340?

CVE-2021-26340 has a CVSS 3.x base score of 8.4, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-26340 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26340?

CVE-2021-26340 primarily affects Amd Epyc 7001 Firmware. In total, 105 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26340?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-26340 published?

CVE-2021-26340 was published on 2021-12-10 and last updated on 2026-06-17.

CVE-2021-26340

CVE-2021-26340 is a high-severity vulnerability in Amd Epyc 7001 Firmware with a CVSS 3.x base score of 8.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 8.4)
CVSS v2: 3.6
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Amd Epyc 7001 Firmware
Published: 2021-12-10
Last modified: 2026-06-17

Description

A malicious hypervisor in conjunction with an unprivileged attacker process inside an SEV/SEV-ES guest VM may fail to flush the Translation Lookaside Buffer (TLB) resulting in unexpected behavior inside the virtual machine (VM).

Frequently asked questions

What is CVE-2021-26340?: A malicious hypervisor in conjunction with an unprivileged attacker process inside an SEV/SEV-ES guest VM may fail to flush the Translation Lookaside Buffer (TLB) resulting in unexpected behavior inside the virtual machine (VM).
How severe is CVE-2021-26340?: CVE-2021-26340 has a CVSS 3.x base score of 8.4, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-26340 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26340?: CVE-2021-26340 primarily affects Amd Epyc 7001 Firmware. In total, 105 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26340?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-26340 published?: CVE-2021-26340 was published on 2021-12-10 and last updated on 2026-06-17.

References

https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1023

Affected products (105)

cpe:2.3:o:amd:epyc_7001_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7232p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7251_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7261_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7252_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_74f3_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7501_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7502_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7502p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7513_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7532_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7542_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7543p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7551_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7551p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7552_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_75f3_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7601_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7642_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7643_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7662_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7663_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7702p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7702_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7713p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7742_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7763_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7f32_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7f52_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7262_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7272_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7281_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7282_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_72f3_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7302_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7301_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7302p_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:epyc_7313_firmware:-:*:*:*:*:*:*:*

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