Security readout for executives and security teams
Plain-English summary
CVE-2021-28191 affects specific ASUS server BMC firmware versions. A privileged remote user of the BMC web management interface can trigger a buffer overflow in the firmware update function, causing the web service to terminate abnormally. The documented impact is availability disruption, not data theft or system takeover.
Executive priority
Treat this as a moderate operational resilience issue for ASUS-managed server hardware. Prioritize Internet-exposed or broadly reachable BMC interfaces first, then remediate affected firmware through vendor guidance during normal infrastructure maintenance windows.
Technical view
The flaw is CWE-120 in the ASUS BMC web firmware update path: user-supplied string length is not verified before handling. CVSS 3.1 is 4.9 with network access, low complexity, high privileges required, no user interaction, and high availability impact only.
Likely exposure
Exposure is most likely where affected ASUS ASMB9-iKVM, RS, ESC, E700, WS, Z11PA, or KNPA systems run the listed BMC firmware versions and the BMC web interface is reachable by privileged users over the network.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires high privileges, so this is mainly a risk from compromised, shared, or misused BMC administrator access, with denial of BMC web service availability as the stated outcome.
Researcher notes
The affected list is version-specific but has no CPEs in the supplied bundle. The public description supports authenticated remote denial of service through a firmware update buffer overflow. It does not support claims of code execution, unauthenticated exploitation, data exposure, or active exploitation.
Mitigation direction
- Inventory ASUS BMC models and firmware versions against the affected list.
- Check ASUS and TWCERT guidance for fixed firmware or vendor-approved remediation.
- Restrict BMC web management access to trusted administrative networks only.
- Review privileged BMC accounts and remove unnecessary administrator access.
- Monitor BMC web service stability until remediation is confirmed.
Validation and detection
- Confirm whether any affected ASUS model and firmware version is present.
- Verify BMC web interfaces are not exposed to untrusted networks.
- Check BMC logs for abnormal web service termination events.
- Confirm firmware update functionality is limited to authorized administrators.
- Document remediation status for each affected BMC asset.
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-2021-28191 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-132-4561-062d0-1.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.