Security readout for executives and security teams
Plain-English summary
A flaw in Windows TCP/IP can let an unauthenticated attacker with adjacent-network access disrupt an affected computer or server. The expected impact is loss of availability, not data theft or modification. Many Windows 10, Windows 11, and Windows Server releases are listed, so unpatched critical infrastructure warrants prompt attention.
Executive priority
Treat this as a prompt high-priority availability fix, especially for critical servers and operationally sensitive Windows systems. It is not rated critical because the documented impact excludes confidentiality and integrity loss, adjacent-network access is required, and the supplied evidence does not establish active exploitation.
Technical view
CVE-2026-40413 is a Windows TCP/IP denial-of-service vulnerability associated with CWE-476, null pointer dereference. CVSS 3.1 scores it 7.4: adjacent-network attack, low complexity, no privileges or user interaction, changed scope, and high availability impact. The supplied sources provide no protocol-path, triggering-condition, or root-cause details.
Likely exposure
Exposure exists where listed Windows 10, Windows 11, or Windows Server releases remain unpatched and attackers can obtain adjacent-network reachability. Critical Windows infrastructure with weak segmentation or strict availability requirements faces the greatest operational concern. The bundle identifies no additional configuration prerequisites.
Exploitation context
The bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or a public proof of concept. CVSS records exploit maturity as unproven. Exploitation nevertheless has low stated complexity and requires neither authentication nor user interaction, although adjacent-network access is required.
Researcher notes
CWE-476 indicates a null pointer dereference, but the sources omit the affected TCP/IP code path, packet conditions, failure behavior, and fixed KB identifiers. The changed-scope rating is source-provided but unexplained. Testing should remain defensive and avoid inferring unsupported protocol or trigger details.
Mitigation direction
- Apply Microsoft's official security update for each affected Windows release, following the MSRC advisory.
- Inventory listed Windows endpoints and servers, then prioritize unpatched systems supporting critical operations.
- Restrict untrusted adjacent-network reachability to critical affected systems until updates are confirmed.
- Check the MSRC advisory for release-specific prerequisites, updates, or revised guidance.
Validation and detection
- Compare discovered Windows editions and builds with the affected-product list.
- Confirm Microsoft's CVE update installed successfully on every in-scope system.
- Use vulnerability-management tooling to verify the CVE no longer reports after remediation.
- Validate representative endpoint, Server Core, and full Server installations separately.
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-476: 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-2026-40413 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
- 7.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/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.
SSVC decision data
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:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:U/RL:O/RC:C2.84microsoftVulnerability scoring details
Base CVSS 3.1 score
7.4HighVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/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 TCP/IP Denial of Service VulnerabilityCVE reference, microsoft · vendor-advisory, patch
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.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.