Security readout for executives and security teams
Plain-English summary
This is a high-severity AMD BIOS issue affecting listed Ryzen 5000 Series platforms. A local low-privileged attacker could potentially move into System Management Mode, a highly privileged firmware context, which can undermine operating-system controls.
Executive priority
Treat this as a firmware-risk item for affected Ryzen 5000 fleets. It is not evidenced as actively exploited, but successful exploitation could bypass normal OS protections, so remediation should be scheduled through firmware management rather than deferred indefinitely.
Technical view
The flaw is improper validation of a BIOS communication buffer and communication service. Tampering with that buffer may lead to arbitrary code execution in SMM. CVSS 3.1 is 7.8 with local attack vector, low complexity, low privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely on systems using affected AMD Ryzen 5000 Series AGESA firmware. The bundle lists Ryzen 2000, Ryzen 3000, and 1st through 3rd Gen EPYC as unaffected.
Exploitation context
No CISA KEV listing or provided source indicates active exploitation. The CVSS vector requires local access and low privileges, so this is mainly a post-compromise privilege, persistence, or firmware-integrity concern rather than a remote entry point.
Researcher notes
Evidence is sufficient for impact, CVSS, and affected-product direction, but the source bundle does not provide specific fixed AGESA versions or detailed mitigation text. Avoid assuming exploit availability, patch identifiers, or affected OEM models beyond the cited AMD scope.
Mitigation direction
- Check AMD SB-1031 and SB-1032 for vendor guidance.
- Inventory Ryzen 5000 systems and their BIOS or AGESA versions.
- Check OEM motherboard or system firmware advisories for CVE-2021-26316.
- Apply vendor-approved BIOS or firmware updates when available.
- Prioritize systems handling sensitive data or privileged administrative work.
Validation and detection
- Confirm whether assets use AMD Ryzen 5000 Series processors.
- Record BIOS, UEFI, motherboard, and AGESA version information.
- Compare firmware status against AMD and OEM advisories.
- Verify listed unaffected platforms are not mistakenly prioritized.
- After updating, confirm firmware version changed as expected.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-20: Exact CWE lookup
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Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-26316 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-1031CVE reference · vendor-advisory
- https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-1032CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.