CVE-2021-26342

CVE-2021-26342 is a low-severity vulnerability in Amd Epyc 7763 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.

Key facts

• Severity: Low (CVSS 3.x base score 3.3)
• CVSS v2: 2.1
• EPSS exploit prediction: 0% (12th percentile)
• Actively exploited: Not listed in CISA KEV
• Affected product: Amd Epyc 7763 Firmware
• Published: 2022-05-11
• Last modified: 2026-06-17

Description

In SEV guest VMs, the CPU may fail to flush the Translation Lookaside Buffer (TLB) following a particular sequence of operations that includes creation of a new virtual machine control block (VMCB). The failure to flush the TLB may cause the microcode to use stale TLB translations which may allow for disclosure of SEV guest memory contents. Users of SEV-ES/SEV-SNP guest VMs are not impacted by this vulnerability.

Frequently asked questions

What is CVE-2021-26342?

In SEV guest VMs, the CPU may fail to flush the Translation Lookaside Buffer (TLB) following a particular sequence of operations that includes creation of a new virtual machine control block (VMCB). The failure to flush the TLB may cause the microcode to use stale TLB translations which may allow for disclosure of SEV guest memory contents. Users of SEV-ES/SEV-SNP guest VMs are not impacted by this vulnerability.

How severe is CVE-2021-26342?

CVE-2021-26342 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-26342 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26342?

CVE-2021-26342 primarily affects Amd Epyc 7763 Firmware. In total, 38 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26342?

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

When was CVE-2021-26342 published?

CVE-2021-26342 was published on 2022-05-11 and last updated on 2026-06-17.

References

• https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1028

Affected products (38)

• cpe:2.3:o:amd:epyc_7763_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7713p_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7713_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7663_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7643_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_75f3_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7543p_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7543_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7513_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7453_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_74f3_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7443p_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7443_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7413_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_73f3_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7343_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7313p_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7313_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_72f3_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7773x_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7473x_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7573x_firmware:*:*:*:*:*:*:*:*
• cpe:2.3:o:amd:epyc_7373x_firmware:*:*:*:*:*:*:*:*
• 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:*:*:*:*:*:*:*:*

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