How severe is CVE-2021-26339?

CVE-2021-26339 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-2021-26339 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26339?

CVE-2021-26339 primarily affects Amd Epyc 7763 Firmware. In total, 84 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-26339?

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

When was CVE-2021-26339 published?

CVE-2021-26339 was published on 2022-05-11 and last updated on 2026-06-17.

CVE-2021-26339

CVE-2021-26339 is a medium-severity vulnerability in Amd Epyc 7763 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.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
CVSS v2: 4.9
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Amd Epyc 7763 Firmware
Published: 2022-05-11
Last modified: 2026-06-17

Description

A bug in AMD CPU’s core logic may allow for an attacker, using specific code from an unprivileged VM, to trigger a CPU core hang resulting in a potential denial of service. AMD believes the specific code includes a specific x86 instruction sequence that would not be generated by compilers.

Frequently asked questions

What is CVE-2021-26339?: A bug in AMD CPU’s core logic may allow for an attacker, using specific code from an unprivileged VM, to trigger a CPU core hang resulting in a potential denial of service. AMD believes the specific code includes a specific x86 instruction sequence that would not be generated by compilers.
How severe is CVE-2021-26339?: CVE-2021-26339 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-2021-26339 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26339?: CVE-2021-26339 primarily affects Amd Epyc 7763 Firmware. In total, 84 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-26339?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-26339 published?: CVE-2021-26339 was published on 2022-05-11 and last updated on 2026-06-17.

References

Affected products (84)

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:ryzen_7_5700g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_7_5700ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_5_5700g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_5_5700ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_3_5300g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_3_5300ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_7_4700g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_7_4700ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_5_4600g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_5_4600ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_3_4300g_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_3_4300ge_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_threadripper_pro_3945wx_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_threadripper_pro_3955wx_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_threadripper_pro_3975wx_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_threadripper_pro_3995wx_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:amd:ryzen_threadripper_pro_5945wx_firmware:-:*:*:*:*:*:*:*

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