What’s Vulnerable › Vulnerabilities

CVE-2021-26339

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2022-05-11 · updated 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.

Affected products

• AMD Epyc 72F3 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7313 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7313P Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7343 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7373X Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 73F3 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7413 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7443 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7443P Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7453 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7473X Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 74F3 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7513 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7543 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7543P Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7573X Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 75F3 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7643 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7663 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7713 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7713P Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7763 Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Epyc 7773X Firmware: before milanpi-sp3_1.0.0.7 — fixed in milanpi-sp3_1.0.0.7
• AMD Ryzen 3 2200U Firmware: all versions
• AMD Ryzen 3 2300U Firmware: all versions
• AMD Ryzen 3 3100 Firmware: all versions
• AMD Ryzen 3 3300G Firmware: all versions
• AMD Ryzen 3 3300X Firmware: all versions
• AMD Ryzen 3 4300G Firmware: before comboam4_v2_pi_1.2.0.6c — fixed in comboam4_v2_pi_1.2.0.6c
• AMD Ryzen 3 4300Ge Firmware: before comboam4_v2_pi_1.2.0.6c — fixed in comboam4_v2_pi_1.2.0.6c

How to fix

Upgrade to a fixed version: AMD Epyc 72F3 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7313 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7313P Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7343 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7373X Firmware milanpi-sp3_1.0.0.7; AMD Epyc 73F3 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7413 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7443 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7443P Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7453 Firmware milanpi-sp3_1.0.0.7; AMD Epyc 7473X Firmware milanpi-sp3_1.0.0.7; AMD Epyc 74F3 Firmware milanpi-sp3_1.0.0.7. Check the vendor advisory for mitigations.

References

• https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1027
• https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1028
• https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1027
• https://www.amd.com/en/corporate/product-security/bulletin/amd-sb-1028

Get alerted when CVE-2021-26339 or the next vulnerability affects your stack