CVE-2021-26402

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-01-11 · updated 2026-06-17
Weakness: CWE-787

Description

Insufficient bounds checking in ASP (AMD Secure Processor) firmware while handling BIOS mailbox commands, may allow an attacker to write partially-controlled data out-of-bounds to SMM or SEV-ES regions which may lead to a potential loss of integrity and availability.

Affected products

AMD Epyc 7002 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7003 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7232P Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7252 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7262 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7272 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7282 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 72F3 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7302 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7302P Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7313 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7313P Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7343 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7352 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7373X Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 73F3 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7402 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7402P Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7413 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7443 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7443P Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7452 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7453 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 74F3 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7502 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7502P Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7513 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4
AMD Epyc 7532 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7542 Firmware: before romepi_1.0.0.c — fixed in romepi_1.0.0.c
AMD Epyc 7543 Firmware: before milanpi_1.0.0.4 — fixed in milanpi_1.0.0.4

How to fix

Upgrade to a fixed version: AMD Epyc 7002 Firmware romepi_1.0.0.c; AMD Epyc 7003 Firmware milanpi_1.0.0.4; AMD Epyc 7232P Firmware romepi_1.0.0.c; AMD Epyc 7252 Firmware romepi_1.0.0.c; AMD Epyc 7262 Firmware romepi_1.0.0.c; AMD Epyc 7272 Firmware romepi_1.0.0.c; AMD Epyc 7282 Firmware romepi_1.0.0.c; AMD Epyc 72F3 Firmware milanpi_1.0.0.4; AMD Epyc 7302 Firmware romepi_1.0.0.c; AMD Epyc 7302P Firmware romepi_1.0.0.c; AMD Epyc 7313 Firmware milanpi_1.0.0.4; AMD Epyc 7313P Firmware milanpi_1.0.0.4. Check the vendor advisory for mitigations.

References

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