Windows: Missing authentication in Windows Error Reporting allows local tampering

Summary

A missing authentication check for a critical function in Windows Error Reporting (WER) allows an authorized local user to tamper with WER data. The attacker needs a low-privilege account on the affected machine, so the flaw is not reachable from the internet. The CVSS base score is 7.1 (High) in NVD and the CNA record, while one mirror shows 5.8 (Medium), so the severity is not yet settled.

Affected

• Windows 10 Version 1607 (10.0.14393.0 to < 10.0.14393.9612)
• Windows 10 Version 1809 (10.0.17763.0 to < 10.0.17763.9376)
• Windows 10 Version 21H2 (10.0.19044.0 to < 10.0.19044.7807)
• Windows 10 Version 22H2 (10.0.19045.0 to < 10.0.19045.7807)
• Windows 11 Version 23H2 (10.0.22631.0 to < 10.0.22631.7652)
• Windows 11 Version 24H2 (10.0.26100.0 to < 10.0.26100.9711)
• Windows 11 Version 25H2 (10.0.26200.0 to < 10.0.26200.9711)
• Windows 11 Version 26H1 (10.0.28000.0 to < 10.0.28000.3231)
• Windows 11 Version 26H2 (10.0.26300.0 to < 10.0.26300.9711)
• Windows Server 2012 and Server Core (6.2.9200.0 to < 6.2.9200.26434)
• Windows Server 2012 R2 and Server Core (6.3.9600.0 to < 6.3.9600.23470)
• Windows Server 2016 (10.0.14393.0 to < 10.0.14393.9612)

Fixed in

• Windows 10 Version 1607 and Windows Server 2016: 10.0.14393.9612
• 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, Windows 11 Version 26H2: 10.0.26100.9711 and 10.0.26200.9711, 10.0.26300.9711
• Windows 11 Version 26H1: 10.0.28000.3231
• Windows Server 2012 and 2012 R2: 6.2.9200.26434 and 6.3.9600.23470
• Installation of the October 2026 cumulative update. The KB number for Windows 10 1607 is unconfirmed.

Workaround

Unknown.

Exploitation

• No exploitation in the wild is known.
• No public proof of concept was found.
• CISA SSVC: Exploitation none, Automatable no, Technical Impact total.

Our recommendation

• Install the October 2026 cumulative update on all affected Windows hosts, starting with Windows 10 1607 and Windows Server 2016.
• Check the exact build numbers against the fixed versions above and verify them against the MSRC Security Update Guide.
• Confirm that Windows 10 1607 is still supported by Microsoft before relying on this patch, because its support status is unverified.
• Prioritise shared and multi-user systems and any unsupported builds.
• Restrict local logon and monitor for unexpected changes to WER data.

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-2026-83715 msrc.microsoft.com
• OpenCVE: CVE-2026-83715 app.opencve.io
• Vulners CVEList: CVE-2026-83715 vulners.com
• Vulners MSCVE: MS:CVE-2026-83715 vulners.com
• Vulners NVD: CVE-2026-83715 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 3 Nov 2026, 14:24.