Security readout for executives and security teams
Plain-English summary
CVE-2021-31974 is a Microsoft Server for NFS denial-of-service flaw. A remote, unauthenticated attacker could disrupt availability on affected Windows systems. The impact is service disruption, not documented data theft or code execution. Microsoft lists an official remediation, and the source bundle does not show CISA KEV listing or confirmed active exploitation.
Executive priority
Treat this as a high-priority availability risk for Windows systems supporting NFS workflows. It is not evidenced as actively exploited in the provided sources, but remote unauthenticated denial of service can interrupt operations. Patch exposed servers first, then complete normal fleet remediation.
Technical view
The CVSS 3.1 vector is 7.5 High: network attack vector, low complexity, no privileges, no user interaction, unchanged scope, and high availability impact only. Affected platforms include multiple Windows 10, Windows 8.1, Windows Server 2012/2012 R2, 2016, 2019, and related Server Core/versioned releases listed by Microsoft/CVE sources.
Likely exposure
Exposure is most relevant to organizations running the affected Windows or Windows Server versions where Microsoft Server for NFS is present and reachable over a network. Systems without that service enabled or reachable are likely lower risk, but the provided sources do not define configuration-specific conditions.
Exploitation context
The source bundle marks CISA KEV as false and the CVSS exploit maturity as unproven. There is no cited evidence here of active exploitation. The vulnerability is still operationally important because unauthenticated network-triggered availability loss can affect file services and dependent workloads.
Researcher notes
The public bundle provides limited technical detail beyond affected products, CVSS, and Microsoft advisory linkage. It supports availability-only impact and official remediation availability. Avoid assuming exploit mechanics, specific ports, or vulnerable configurations beyond Server for NFS on affected Windows versions.
Mitigation direction
- Apply the Microsoft security update for CVE-2021-31974 from the MSRC advisory.
- Prioritize exposed Windows servers providing NFS-related services.
- Limit unnecessary network reachability to Server for NFS while remediation is pending.
- Check Microsoft guidance for any product-specific servicing requirements.
- Track unsupported or legacy affected systems for upgrade or isolation decisions.
Validation and detection
- Inventory Windows assets against the affected products and builds in the advisory.
- Confirm whether Server for NFS is enabled and network reachable.
- Verify installed Microsoft updates close CVE-2021-31974 on each affected host.
- Run authenticated vulnerability scans after patching to confirm remediation.
- Review availability monitoring for unexplained NFS service disruption.
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.
CVE-2021-31974 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
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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-2021-31974CVE 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.