Security readout for executives and security teams
Plain-English summary
This is a critical Microsoft Windows HTTP.sys flaw that could let an unauthenticated network attacker run code on affected systems. The source bundle lists many supported Windows client and server versions and identifies Microsoft guidance as patched. Business urgency is highest for systems reachable from untrusted networks.
Executive priority
Treat this as emergency patching for exposed Windows servers and high-priority patching for affected endpoints. The combination of unauthenticated network RCE and broad Windows impact creates material business risk, even without confirmed exploitation in the provided sources.
Technical view
CVE-2026-47291 is an integer overflow or wraparound in Windows HTTP.sys, mapped to CWE-190 and CWE-122. The CVSS 3.1 score is 9.8 with network attack vector, low complexity, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is likely on affected Windows versions where HTTP.sys processes network HTTP traffic. The sources do not define required roles, services, ports, or configurations, so teams should inventory affected builds and verify Microsoft-specific applicability.
Exploitation context
No active exploitation is supported by the provided bundle: KEV is false and exploit code maturity is listed as unproven. Risk remains severe because the vulnerability is unauthenticated, network-reachable, low-complexity RCE with complete impact ratings.
Researcher notes
The bundle confirms severity, affected Windows versions, weakness classes, and patch availability, but does not provide protocol details, trigger conditions, exploit telemetry, or compensating controls. Avoid assuming service-specific exposure beyond HTTP.sys until Microsoft guidance or local testing confirms it.
Mitigation direction
- Apply the Microsoft security update for CVE-2026-47291.
- Prioritize affected systems reachable from untrusted networks.
- Review MSRC guidance for product-specific update details.
- Do not rely on undocumented workarounds from secondary sources.
Validation and detection
- Compare Windows build versions against the affected list.
- Confirm Microsoft updates for CVE-2026-47291 are installed.
- Identify systems where HTTP.sys handles network HTTP traffic.
- Track MSRC for revised affected versions or mitigations.
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.
CWE-122: 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 lookupCWE-190: 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 lookupExecution 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-2026-47291 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.
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: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
- HTTP.sys Remote Code Execution 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.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.