Security readout for executives and security teams
Plain-English summary
This is a critical AMD firmware vulnerability in the Secure Processor bootloader. If a malicious AMD Secure Processor application or bootloader component can issue malformed system calls, the platform may suffer denial of service and integrity impact. The source bundle does not show public exploitation or exact fixed firmware versions.
Executive priority
Treat as high-priority firmware risk for AMD fleets, especially servers and managed endpoints. Urgency is driven by critical integrity and availability impact, but prioritization should account for missing exploitation evidence and the need for OEM-specific firmware confirmation.
Technical view
CVE-2021-46756 is insufficient input validation in SVC_MAP_USER_STACK in the AMD Secure Processor bootloader. The described attacker path requires a malicious Uapp or ABL sending malformed or invalid syscalls. Impact is high integrity and high availability loss, with no confidentiality impact in the provided CVSS vector.
Likely exposure
Exposure is most relevant to systems using listed AMD Ryzen, Threadripper, Athlon, and EPYC platforms with affected AGESA or OEM firmware. The bundle lists broad product families and “various” versions, so exact exposure requires firmware inventory and vendor advisory matching.
Exploitation context
The bundle does not indicate CISA KEV listing or active exploitation. It describes a malformed syscall from a malicious Uapp or ABL, which suggests exploitation depends on reaching privileged firmware-related execution context rather than ordinary application access.
Researcher notes
Key uncertainty is affected and fixed version specificity. The public bundle identifies broad product families and AGESA but not precise vulnerable firmware builds. Avoid assuming network-reachable exploitation beyond the supplied CVSS vector and AMD description.
Mitigation direction
- Review AMD SB-4001 and SB-3001 for affected platform guidance.
- Check OEM BIOS or firmware updates for listed AMD platforms.
- Prioritize AGESA or firmware updates on exposed EPYC and endpoint fleets.
- Track systems where firmware cannot be updated promptly.
- Apply vendor guidance rather than substituting unverified workarounds.
Validation and detection
- Inventory AMD CPU families and current BIOS or firmware versions.
- Map systems against AMD and OEM advisory applicability.
- Confirm whether installed firmware includes updated AGESA guidance.
- Check vulnerability scanners for CVE-2021-46756 firmware detections.
- Document systems with no available OEM update path.
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-2021-46756 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
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H3.95.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
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.