HighCVE-2021-26338

    AMD 2nd Gen AMD EPYC™: Improper Access Control (CVE-2021-26338)

    Published Sources: CVE.org

    What is affected, what to do

    Improper access controls in System Management Unit (SMU) may allow for an attacker to override performance control tables located in DRAM resulting in a potential lack of system resources.

    Update AMD Epyc 7f72 Firmware to version romepi-sp3_1.0.0.c, AMD Epyc 7f52 Firmware to version romepi-sp3_1.0.0.c, AMD Epyc 7f32 Firmware to version romepi-sp3_1.0.0.c.

    Affected
    • AMD Epyc 7f72 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7f52 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7f32 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7h12 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7742 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7702 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7702p Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7662 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7642 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7552 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7542 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7532 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7502 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7502p Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7452 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7402 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7402p Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7352 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7302 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7302p Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7282 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7272 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7262 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7252 Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7232p Firmware lt *..romepi-sp3_1.0.0.c
    • AMD Epyc 7763 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7713p Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7713 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7663 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7643 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 75f3 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7543p Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7543 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7513 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7453 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 74f3 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7443p Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7443 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7413 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 73f3 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7343 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7313p Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 7313 Firmware lt *..milanpi-sp3_1.0.0.4
    • AMD Epyc 72f3 Firmware lt *..milanpi-sp3_1.0.0.4
    Fixed in
    • AMD Epyc 7f72 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7f52 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7f32 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7h12 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7742 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7702 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7702p Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7662 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7642 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7552 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7542 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7532 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7502 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7502p Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7452 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7402 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7402p Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7352 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7302 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7302p Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7282 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7272 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7262 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7252 Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7232p Firmware romepi-sp3_1.0.0.c
    • AMD Epyc 7763 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7713p Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7713 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7663 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7643 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 75f3 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7543p Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7543 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7513 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7453 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 74f3 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7443p Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7443 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7413 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 73f3 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7343 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7313p Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 7313 Firmware milanpi-sp3_1.0.0.4
    • AMD Epyc 72f3 Firmware milanpi-sp3_1.0.0.4

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    0.9 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 60.4

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    66.66 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.9 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    60.4
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-284

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Improper access controls in System Management Unit (SMU) may allow for an attacker to override performance control tables located in DRAM resulting in a potential lack of system resources.

    Source: NVD (NIST), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    AMD2nd Gen AMD EPYC™
    • —
    • —
    AMD3rd Gen AMD EPYC™
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Otheramdepyc_7232p_firmware—
    Otheramdepyc_7252_firmware—
    Otheramdepyc_7262_firmware—
    Otheramdepyc_7272_firmware—
    Otheramdepyc_7282_firmware—
    Otheramdepyc_72f3_firmware—
    Otheramdepyc_7302_firmware—
    Otheramdepyc_7302p_firmware—
    Otheramdepyc_7313_firmware—
    Otheramdepyc_7313p_firmware—
    Otheramdepyc_7343_firmware—
    Otheramdepyc_7352_firmware—
    Otheramdepyc_73f3_firmware—
    Otheramdepyc_7402_firmware—
    Otheramdepyc_7402p_firmware—
    Otheramdepyc_7413_firmware—
    Otheramdepyc_7443_firmware—
    Otheramdepyc_7443p_firmware—
    Otheramdepyc_7452_firmware—
    Otheramdepyc_7453_firmware—
    Otheramdepyc_74f3_firmware—
    Otheramdepyc_7502_firmware—
    Otheramdepyc_7502p_firmware—
    Otheramdepyc_7513_firmware—

    Weakness classes (CWE)

    • CWE-284Improper Access Control

      Pillar

      The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.

      Entry at MITRE CWE-284

    References & sources

    • amd.comen/corporate/product-security/bulletin/amd-sb-1021x_refsource_MISC, Vendor advisory
    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2021-26338
    <a href="https://intel.neosec.eu/en/cve/CVE-2021-26338"><img src="https://intel.neosec.eu/badge/cve/CVE-2021-26338.svg?lang=en" alt="CVE-2021-26338 – NEOSEC Intel" height="20"></a>