Security readout for executives and security teams
Plain-English summary
This flaw lets a highly privileged person with physical access weaken Secure Boot protections on affected Cisco UCS-based systems by installing firmware that permits bypassing image validation. Business impact is serious if an attacker already has hands-on access to critical infrastructure, but the access requirements limit broad internet-scale risk.
Executive priority
Treat this as a moderate-priority infrastructure integrity issue. It is not a remote mass-exploitation scenario, but compromise could undermine boot trust on critical Cisco-based systems where an attacker has privileged physical access.
Technical view
CVE-2019-1736 is an improper firmware image validation issue in Cisco UCS C-Series Rack Server firmware affecting Cisco UCS-based products. An authenticated physical attacker with high privileges could install a firmware version that allows UEFI Secure Boot to be disabled, then boot a Cisco-unsigned software image.
Likely exposure
Exposure is most likely in environments running affected Cisco UCS-based products. The provided bundle specifically lists Cisco Identity Services Engine Software and describes Cisco UCS C-Series Rack Server firmware, but version details are not included here.
Exploitation context
The source bundle does not report active exploitation, and the CVE is not listed as KEV. Exploitation requires physical access, authentication, and high privileges, so this is mainly a data center, insider, supply-chain, or maintenance-access risk.
Researcher notes
The weakness maps to CWE-347 and centers on improper firmware upgrade image validation. The CVSS vector is physical access, low complexity, high privileges, no user interaction, unchanged scope, and high confidentiality, integrity, and availability impact.
Mitigation direction
- Review Cisco advisory cisco-sa-20200219-ucs-boot-bypass for affected releases and vendor fixes.
- Inventory Cisco UCS-based systems and Cisco ISE deployments in managed infrastructure.
- Restrict physical access to servers and management interfaces.
- Limit firmware upgrade privileges to tightly controlled administrator roles.
- Review firmware update and maintenance procedures for unauthorized changes.
Validation and detection
- Compare deployed Cisco firmware and product versions against Cisco advisory guidance.
- Confirm affected UCS-based assets are tracked in vulnerability management scope.
- Review firmware update logs for unexpected downgrade or upgrade activity.
- Verify physical access controls around affected servers and maintenance workflows.
- Check administrator access lists for unnecessary firmware management privileges.
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-347: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2019-1736 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
- 6.2 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:P/AC:L/PR:H/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:3.0/AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.35.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.2MediumVector: CVSS:3.0/AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200219 Multiple Cisco UCS-Based Products UEFI Secure Boot Bypass VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
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.
Improper Verification of Cryptographic Signature
Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.