Microsoft Windows BITS: Heap-based buffer overflow allows local privilege escalation

Summary

A heap-based buffer overflow in the Windows Background Intelligent Transfer Service (BITS) allows an authorized local user with low privileges to elevate their privileges. Successful exploitation would give an attacker high impact on confidentiality, integrity and availability of the affected system. The attack requires local access and a valid low-privileged account, so it is not directly reachable from the internet.

Affected

• Microsoft Windows 10 Version 1607 (10.0.14393.0 to before 10.0.14393.9612)
• Microsoft Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9376)
• Microsoft Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7807)
• Microsoft Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7807)
• Microsoft Windows 11 Version 23H2 (10.0.22631.0 to before 10.0.22631.7652)
• Microsoft Windows 11 Version 24H2 (10.0.26100.0 to before 10.0.26100.9711)
• Microsoft Windows 11 Version 25H2 (10.0.26200.0 to before 10.0.26200.9711)
• Microsoft Windows 11 Version 26H1 (10.0.28000.0 to before 10.0.28000.3231)
• Microsoft Windows 11 Version 26H2 (10.0.26300.0 to before 10.0.26300.9711)
• Microsoft Windows Server 2012 and Server Core installation (6.2.9200.0 to before 6.2.9200.26434)
• Microsoft Windows Server 2012 R2 and Server Core installation (6.3.9600.0 to before 6.3.9600.23470)
• Microsoft Windows Server 2016 (10.0.14393.0 to before 10.0.14393.9612)
• The CPE data lists only Windows 10 1607; the CVE record lists the products above.

Fixed in

• Windows 10 Version 1607 and Server 2016: 10.0.14393.9612 (per aggregator data; verify on the MSRC page)
• Windows 10 Version 1809: 10.0.17763.9376
• Windows 10 Version 21H2: 10.0.19044.7807
• Windows 10 Version 22H2: 10.0.19045.7807
• Windows 11 Version 23H2: 10.0.22631.7652
• Windows 11 Version 24H2 and 25H2: 10.0.26100.9711 and 10.0.26200.9711
• Windows 11 Version 26H1: 10.0.28000.3231
• Windows 11 Version 26H2: 10.0.26300.9711
• Windows Server 2012 and 2012 R2: 6.2.9200.26434 and 6.3.9600.23470
• Fixed KB numbers for Windows 10 1607: Unknown. Check the MSRC advisory.

Workaround

• The CVE record and Microsoft's data provide no workaround.
• Interim option (third-party suggestion, not from Microsoft): restrict BITS to trusted use or disable the BITS service where background transfers are not required. Test first, because Windows Update and other software may depend on BITS.

Exploitation

• Exploitation in the wild: none confirmed for this CVE. CISA SSVC lists exploitation as none.
• Public proof of concept: none known. VulDB states that no exploit is available.
• EPSS was about 0.37 percent in mid-October 2026, indicating low predicted exploitation.

Our recommendation

• Install the Microsoft security update for October 2026 on all affected systems, prioritising servers and multi-user systems.
• Confirm the fixed build and KB number for your edition on the MSRC page before rollout.
• Check whether Windows 10 1607 (LTSB 2016) still receives updates; if not, plan an upgrade or isolate the system.
• Limit local logon rights and monitor for unusual privilege escalation or BITS activity.
• Check the CISA KEV catalog for changes in exploitation status.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-85848 msrc.microsoft.com
• VulDB: CVE-2026-85848 vuldb.com
• Vulners NVD entry: CVE-2026-85848 vulners.com
• Vulners MSCVE entry: MS:CVE-2026-85848 vulners.com
• OpenCVE: CVE-2026-85848 app.opencve.io
• Strix: CVE-2026-85848 www.strix.ai
• Qualys Patch Tuesday October 2026 review blog.qualys.com
• Vulnrichment: CVE-2026-85848 vulners.com

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, 02:02.