Security readout for executives and security teams
Plain-English summary
CVE-2021-28340 is a high-severity Microsoft Windows Remote Procedure Call Runtime remote code execution flaw. A successful attack could let an authenticated, low-privileged attacker run code without user interaction, creating serious confidentiality, integrity, and availability risk on unpatched Windows systems.
Executive priority
Treat as high priority because the flaw can enable remote code execution with low privileges and no user interaction. Patch affected Windows systems through normal emergency or accelerated maintenance channels.
Technical view
The CVSS 3.1 vector is AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H with score 8.8. The source bundle lists multiple Windows client and server versions, including Windows 7, 8.1, Windows 10 releases, and Windows Server 2008, 2016, and 2019 variants.
Likely exposure
Exposure is most likely on unpatched Windows endpoints and servers matching the listed affected versions. Legacy Windows systems and server-core installations require attention because they are explicitly included in the affected product list.
Exploitation context
The bundle does not identify active exploitation, and KEV is false. The CVSS exploit maturity is marked unproven, so treat this as a serious patching priority, not as confirmed in-the-wild exploitation.
Researcher notes
Evidence is limited to the CVE and Microsoft advisory references in the bundle. No CWE, exploit details, or active exploitation confirmation are provided. Avoid assuming specific RPC exposure paths beyond the stated network attack vector.
Mitigation direction
- Inventory Windows endpoints and servers against the affected versions listed in the CVE bundle.
- Apply the applicable Microsoft security update from MSRC guidance for each affected operating system.
- Prioritize internet-facing, server, and legacy Windows assets first.
- Check Microsoft guidance for any version-specific prerequisites or support limitations.
Validation and detection
- Confirm each affected asset reports the relevant Microsoft security update as installed.
- Re-run vulnerability scanning after patching to verify CVE-2021-28340 is cleared.
- Review asset inventory for unsupported Windows versions still present.
- Document exceptions with compensating controls and remediation owners.
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.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-28340 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
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:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-28340CVE 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.