Security readout for executives and security teams
Plain-English summary
This issue affects specific ASUS BMC firmware used to remotely manage servers and workstations. A privileged remote user can enter overly long SMTP configuration data and crash the BMC web service. The main business impact is loss of management-plane availability, not data theft or code execution based on the supplied sources.
Executive priority
Treat this as a management-plane availability issue. It is not described as unauthenticated or data-compromising, but BMC outages can disrupt remote server operations. Prioritize exposed or shared-administration BMC environments first.
Technical view
CVE-2021-28193 is a CWE-120 buffer overflow in the SMTP configuration function of ASUS BMC web management pages. The CVSS vector is AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H, meaning network reachable, low complexity, high privileges required, and availability-only impact.
Likely exposure
Exposure is limited to listed ASUS BMC firmware versions on ASMB9-iKVM and specific ASUS server, workstation, and motherboard platforms. Risk increases if the BMC web interface is reachable beyond a restricted management network or has broadly shared privileged accounts.
Exploitation context
The source bundle does not show CISA KEV listing, active exploitation, public exploit details, or weaponized guidance. The described attack requires privileged permission and can abnormally terminate the web service through the vulnerable SMTP configuration path.
Researcher notes
The affected list is version-specific and broad across ASUS BMC platforms. Evidence does not identify fixed versions in the supplied bundle, so validation should focus on asset matching, BMC reachability, privilege model, and vendor advisory follow-up.
Mitigation direction
- Review ASUS and TWCERT guidance for fixed firmware or official mitigation for each affected model.
- Update affected BMC firmware only to vendor-approved versions after maintenance-window testing.
- Restrict BMC web management access to dedicated management networks and trusted administrators.
- Remove internet exposure from BMC interfaces and enforce strong admin access controls.
- Monitor BMC web service restarts and failed administrative actions.
Validation and detection
- Inventory ASUS systems using ASMB9-iKVM or listed BMC firmware.
- Compare BMC firmware versions against the affected versions in the CVE record.
- Confirm BMC web interfaces are unreachable from untrusted networks.
- Review logs for unexpected BMC web service termination around SMTP configuration changes.
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-120: 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-2021-28193 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
- 4.9 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/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:H/UI:N/S:U/C:N/I:N/A:H1.23.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.9MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.asus.com/content/ASUS-Product-Security-Advisory/CVE reference · x_refsource_MISC
- https://www.asus.com/tw/support/callus/CVE reference · x_refsource_MISC
- https://www.twcert.org.tw/tw/cp-132-4563-e4092-1.htmlCVE reference · x_refsource_MISC
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.
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.