Security readout for executives and security teams
Plain-English summary
CVE-2021-26371 is an AMD firmware-related information disclosure issue. A compromised or malicious boot component could trigger a bootloader SHA256 system call and expose AMD Secure Processor memory to userspace. This is not described as remote exploitation, but leaked privileged memory can matter on shared or already-compromised systems.
Executive priority
Treat this as a moderate firmware hygiene item, not an emergency based on the provided evidence. Prioritize systems with sensitive workloads or local multi-user exposure, and fold remediation into BIOS or platform firmware maintenance cycles once vendor guidance is confirmed.
Technical view
The issue involves AGESA/bootloader handling where a compromised or malicious ABL or UApp sends a SHA256 system call to the bootloader, potentially exposing ASP memory to userspace. CVSS 3.1 is 5.5: local attack vector, low complexity, low privileges, no user interaction, high confidentiality impact only.
Likely exposure
Exposure is most relevant to organizations running AMD Ryzen, Threadripper, Athlon mobile, or EPYC platforms named in AMD advisories. The provided bundle does not include exact vulnerable or fixed AGESA versions, CPEs, or OEM BIOS mappings, so exposure requires asset and firmware verification.
Exploitation context
The sources do not show CISA KEV listing or active exploitation. The CVSS vector indicates local access with low privileges, not remote pre-authentication compromise. Practical risk is higher where attackers may already have local code execution or where systems are shared, high-value, or difficult to patch.
Researcher notes
Key gaps are version specificity and OEM mapping. The bundle identifies affected product families and AGESA context but does not provide exploit artifacts, fixed AGESA versions, or proof of exploitation. Analysis should stay focused on firmware provenance, AMD advisory applicability, and confidentiality exposure from ASP memory leakage.
Mitigation direction
- Review AMD-SB-4001 and AMD-SB-3001 for affected platform guidance.
- Inventory systems using the listed AMD processor families.
- Check OEM BIOS or firmware updates containing relevant AGESA updates.
- Prioritize firmware updates for shared, sensitive, or externally managed endpoints.
- Monitor AMD and OEM advisories for fixed version details.
Validation and detection
- Map hardware models to the AMD platform families listed in the advisories.
- Record current BIOS, firmware, and AGESA versions where visible.
- Compare OEM firmware release notes against AMD advisory references.
- Confirm firmware update availability through the system vendor.
- Document systems where fixed-version evidence is unavailable.
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.
CVE-2021-26371 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
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:N/A:N1.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-4001CVE reference · vendor-advisory
- https://www.amd.com/en/corporate/product-security/bulletin/AMD-SB-3001CVE 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.