Microsoft Windows IME: Elevation of privilege due to weak authentication
Summary
A weak authentication flaw in the Microsoft Input Method Editor (IME) component of Windows allows an authorized local attacker to elevate privileges. The attacker needs local access and a valid low-privilege account, so the vulnerability is not remotely exploitable. Microsoft does not publicly describe the mechanism, and no exploitation has been reported.
Affected
- Windows 10 Version 1607 (below 10.0.14393.9612)
- Windows 10 Version 1809 (below 10.0.17763.9376)
- Windows 10 Version 21H2 (below 10.0.19044.7807)
- Windows 10 Version 22H2 (below 10.0.19045.7807)
- Windows 11 Version 23H2 (below 10.0.22631.7652)
- Windows 11 Version 24H2 (below 10.0.26100.9711)
- Windows 11 Version 25H2 (below 10.0.26200.9711)
- Windows 11 Version 26H1 (below 10.0.28000.3231)
- Windows 11 Version 26H2 (below 10.0.26300.9711)
- Windows Server 2012 and 2012 R2 (including Server Core)
- Windows Server 2016 (below 10.0.14393.9612)
Fixed in
Security updates from Microsoft's October 2026 release, with fixed builds as listed under affected versions. Check the MSRC page for the exact KB numbers per product.
Workaround
Unknown. No workaround is documented in the sources.
Exploitation
- No evidence of exploitation in the wild found.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Install the October 2026 Windows security updates on all affected systems, prioritising multi-user terminal and file servers.
- Limit local logon to trusted users and remove unnecessary local accounts on shared machines.
- Monitor endpoints for privilege escalation activity until patching is complete.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Microsoft Input Method Editor (IME)
- 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-2026-88101 msrc.microsoft.com
- Vulners: CVE-2026-88101 (CNA record) vulners.com
- OffSeq Radar: CVE-2026-88101 radar.offseq.com
- Strix: CVE-2026-58534 (related IME flaw) 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, 01:24.
Original description (NVD)
Weak authentication in Microsoft Input Method Editor (IME) allows an authorized attacker to elevate privileges 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.
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