Security readout for executives and security teams
Plain-English summary
A flaw in Windows HTTP.sys could let an unauthenticated remote attacker run code on a reachable system. No user action or account is required. Successful exploitation could expose data, alter systems, or disrupt services. The supplied record identifies numerous supported Windows desktop and server versions as affected.
Executive priority
Treat this as an accelerated, critical remediation effort. Direct teams to patch exposed systems first, establish temporary network restrictions where immediate patching is impossible, and report coverage and exceptions. Although active exploitation is not established by the supplied evidence, the unauthenticated network attack path and potential full system impact justify urgent action.
Technical view
CVE-2026-47291 is an HTTP.sys integer overflow or wraparound vulnerability associated with CWE-190 and heap-based buffer overflow CWE-122. It is remotely reachable with low attack complexity, requires neither privileges nor user interaction, and can compromise confidentiality, integrity, and availability. Its CVSS 3.1 score is 9.8.
Likely exposure
Exposure is highest where affected Windows systems run HTTP.sys-backed services reachable from untrusted networks. The supplied affected list spans Windows 10, Windows 11, and Windows Server 2012 through 2025, including several Server Core installations. Confirm actual exposure through service, reachability, version, and update-state inventories.
Exploitation context
The supplied bundle does not establish active exploitation, and the CVE is not marked as included in CISA KEV. The CVSS vector records exploit maturity as unproven. This does not establish safety: unauthenticated network reachability, low complexity, and potential code execution make exposed systems attractive targets.
Researcher notes
The record attributes the condition to integer wraparound and heap-based memory corruption in HTTP.sys but provides no triggering details. The affected entries include duplicate naming for Windows 11 23H2 and base version identifiers rather than confirmed vulnerable patch levels. Use Microsoft's advisory and update applicability data for precise host-level determinations.
Mitigation direction
- Apply Microsoft's official security update for each affected Windows version as soon as operationally possible.
- Prioritize internet-facing and externally reachable systems using HTTP.sys-backed services.
- Restrict untrusted network access to affected HTTP services until updates are confirmed.
- Check Microsoft guidance for version-specific prerequisites, mitigations, and servicing instructions.
Validation and detection
- Inventory systems matching the Windows versions listed in the CVE record.
- Identify HTTP.sys-backed services and determine whether untrusted networks can reach them.
- Verify the applicable Microsoft security update is installed successfully on each system.
- Re-scan patched systems and confirm exposed services remain operational and appropriately restricted.
- Monitor vendor and CVE records for revised affected versions or exploitation information.
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.