Security readout for executives and security teams
Plain-English summary
This critical flaw affects Microsoft’s Windows Services for NFS component across multiple Windows 10, Windows 8.1, and Windows Server releases. A network attacker may exploit it without credentials or user interaction, potentially taking control of an affected system or disrupting operations. Prompt patch verification is warranted, especially where NFS services are present.
Executive priority
Treat as an urgent remediation item for affected systems, prioritizing servers and any NFS-enabled hosts reachable from untrusted networks. The potential impact is system compromise without authentication. Balance urgency with the absence of supplied evidence for active exploitation, and require asset-level confirmation rather than assuming every listed Windows installation is exposed.
Technical view
CVE-2021-26432 is a remote-code-execution vulnerability in the Windows Services for NFS ONCRPC XDR driver. Its CVSS 3.1 score is 9.8: network-accessible, low complexity, no privileges or user interaction required, with potentially high confidentiality, integrity, and availability impact. The supplied sources do not describe the root cause, affected configurations, or attack mechanics.
Likely exposure
The listed scope includes Windows 8.1, several Windows 10 releases, and Windows Server 2012 through 2019 plus versions 2004 and 20H2, including Server Core variants. Actual exposure depends on whether the vulnerable NFS component and an affected build are present. The supplied evidence does not define configuration prerequisites or service reachability requirements.
Exploitation context
The CVSS vector indicates remote, unauthenticated exploitation with low attack complexity and no user interaction. However, the supplied record is not in CISA KEV and provides no cited evidence of exploitation in the wild. Public exploit availability is not established by this source bundle.
Researcher notes
The bundle provides a CVSS vector and product list but no CWE, root-cause analysis, protocol details, vulnerable function, proof of concept, or specific update identifiers. Researchers should use Microsoft’s advisory to map builds to updates and establish configuration prerequisites. Do not infer active exploitation from the 2026 record update timestamp alone.
Mitigation direction
- Identify listed Windows versions running or containing Windows Services for NFS.
- Review Microsoft’s advisory for the update applicable to each operating-system release.
- Apply the Microsoft security update through the organization’s approved patch process.
- Prioritize systems where NFS services are exposed to untrusted networks.
- If immediate patching is impossible, obtain supported temporary mitigations from Microsoft guidance.
Validation and detection
- Inventory operating-system builds against the affected list in the CVE record.
- Determine whether Windows Services for NFS is installed or enabled on each system.
- Verify the applicable Microsoft security update is installed successfully.
- Confirm patched systems completed required restarts and report healthy update status.
- Reassess network reachability to NFS services after remediation.
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-2021-26432 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/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:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C3.95.9microsoftVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- Windows Services for NFS ONCRPC XDR Driver Remote Code Execution VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26432CVE reference, CVE · 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.