Security readout for executives and security teams
Plain-English summary
CVE-2021-1671 is a Microsoft Windows Remote Procedure Call Runtime flaw that could let a low-privileged remote attacker execute code without user interaction. The source bundle rates it high severity with full confidentiality, integrity, and availability impact. Evidence provided does not show active exploitation.
Executive priority
Treat as a high-priority Windows patching item, particularly for servers and legacy systems. The business urgency is driven by remote code execution potential and broad Windows coverage, not by confirmed exploitation in the provided evidence.
Technical view
The CVSS 3.1 vector is 8.8 high: network attack vector, low complexity, low privileges required, no user interaction, unchanged scope, and high CIA impact. Affected products are multiple Windows client and server releases, including Server Core variants, from Windows Server 2008 through Windows Server 20H2 and Windows 10 releases.
Likely exposure
Organizations running affected Microsoft Windows client or server versions are potentially exposed, especially where RPC services are reachable by low-privileged users over the network. The bundle does not identify non-Windows products or specific exposed ports.
Exploitation context
The bundle marks KEV as false and CVSS exploit maturity as unproven, so active exploitation should not be claimed from these sources. Risk remains material because the vulnerability is network-reachable, low-complexity, and does not require user interaction.
Researcher notes
The provided data is thin beyond MSRC, CVSS, and affected-product metadata. Do not infer exploit chains, affected components beyond RPC Runtime, or compensating controls not named by Microsoft. The CPE list appears broad and should be validated against MSRC build-specific update guidance.
Mitigation direction
- Review the Microsoft MSRC advisory for the exact update applicable to each Windows build.
- Apply Microsoft’s official security updates where available for affected systems.
- Prioritize servers, domain infrastructure, and broadly reachable Windows systems for remediation.
- Check Microsoft guidance for legacy or extended-support Windows versions.
- Track any later vendor or KEV status changes before reporting exploitation claims.
Validation and detection
- Inventory Windows client and server versions against the affected product list.
- Verify installed security updates against the Microsoft advisory for CVE-2021-1671.
- Confirm whether affected RPC-capable systems are reachable by low-privileged network users.
- Document systems that require legacy support or cannot receive official updates.
- Reassess exposure after patching using normal vulnerability management scans.
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-2021-1671 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
- Remote Procedure Call Runtime Remote Code Execution VulnerabilityCVE reference · vendor-advisory
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1671CVE reference · x_refsource_MISC, x_transferred
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.