Microsoft Windows HTTP.sys: Out-of-bounds read enables local code execution
Summary
An out-of-bounds read in the Windows HTTP.sys kernel driver allows an authorized local attacker to execute code. The attacker needs local access and low privileges, and no user interaction is required. Microsoft's advisory title mentions remote code execution, but the CVE description and CVSS vector (AV:L) describe a local attack, so verify the attack path on MSRC. Microsoft has published fixes for affected builds.
Affected
- Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9612
- Windows 10 Version 1809: 10.0.17763.0 to before 10.0.17763.9376
- Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7807
- Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7807
- Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7652
- Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9711
- Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9711
- Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3231
- Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9711
- Windows Server 2012 (incl. Server Core): 6.2.9200.0 to before 6.2.9200.26434
- Windows Server 2012 R2 (incl. Server Core): 6.3.9600.0 to before 6.3.9600.23470
- Windows Server 2016: 10.0.14393.0 to before 10.0.14393.9612
Fixed in
- Windows 10 1607 and Windows Server 2016: 10.0.14393.9612
- Windows 10 1809: 10.0.17763.9376
- Windows 10 21H2: 10.0.19044.7807
- Windows 10 22H2: 10.0.19045.7807
- Windows 11 23H2: 10.0.22631.7652
- Windows 11 24H2, 25H2 and 26H2: 10.0.26100.9711 / 10.0.26200.9711 / 10.0.26300.9711
- Windows 11 26H1: 10.0.28000.3231
- Windows Server 2012: 6.2.9200.26434
- Windows Server 2012 R2: 6.3.9600.23470
Source: CNA record. Verify the complete list on MSRC before rollout.
Workaround
Unknown. No workaround is confirmed in the available sources; apply Microsoft's update.
Exploitation
No exploitation or public proof of concept found in the research notes (as of 2 Nov 2026). CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
Our recommendation
- Inventory all Windows systems, including Windows 10 1607, 1809, 21H2, 22H2 and Windows Server versions, not only the CPE-listed product.
- Install the Microsoft security update for each affected build as soon as possible and verify the installed build number.
- Check whether Windows 10 1607 LTSB is still supported and plan an upgrade if it is not (check Microsoft's lifecycle page).
- Limit local logon and restrict low-privileged accounts on servers that run IIS or other HTTP.sys-based services.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Remote code execution – Windows HTTP.sys
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-70247 msrc.microsoft.com
- Vulners: CNA record CVELIST:CVE-2026-70247 vulners.com
- Vulners: NVD record CVE-2026-70247 vulners.com
- OpenCVE: CVE-2026-70247 app.opencve.io
- Strix: CVE-2026-70247 www.strix.ai
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 2 Nov 2026, 03:55.
Original description (NVD)
Out-of-bounds read in Windows HTTP.sys allows an authorized attacker to execute code locally.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.