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Response snapshot Oct 27, 2026, 03:11 UTC

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Advisoryproject-zero-windows-dangling-com-aeff1dc7e91a

Windows Exploitation Techniques: Dangling COM Object Registrations

This short blog post is about abusing a privilege escalation bug that Microsoft recently fixed in Windows, CVE-2026-66804, that I and 14 others reported. This issue is an incomplete fix for CVE-2026-50343, a bug dubbed “Dark Elevator” by Calif.

At a glance

Sources
1 source

What to do

Read the exact official research article before applying its defensive techniques or drawing conclusions.

Read Google Project Zero Research: Windows Exploitation Techniques: Dangling COM Object Registrations (opens a new tab)

What happened

This short blog post is about abusing a privilege escalation bug that Microsoft recently fixed in Windows, CVE-2026-66804, that I and 14 others reported. This issue is an incomplete fix for CVE-2026-50343, a bug dubbed “Dark Elevator” by Calif. The root cause of the bug was a dangling COM object registration for the CrossDevice COM object with the CLSID {E9F83CF2-E0C0-4CA7-AF01-E90C70BEF496}.

A COM registration typically needs two parts: a server executable, which for in-process components is a DLL and a CLSID entry under the HKEY_CLASSES_ROOT registry key which points to that DLL.

Sources

  1. Primary source

    Google Project Zero Research: Windows Exploitation Techniques: Dangling COM Object Registrations (opens a new tab)

    Exact official article/advisory identified by the feed; title, source dates, and any supplied article excerpt.

    Published Checked

  2. Primary source

    Google Project Zero Research syndication feed (opens a new tab)

    The RSS/Atom/RDF entry supplied this exact link and any available title, date, and excerpt.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, September 21). Windows Exploitation Techniques: Dangling COM Object Registrations. https://kevwire.com/record/project-zero-windows-dangling-com-aeff1dc7e91a

MLA

"Windows Exploitation Techniques: Dangling COM Object Registrations." KEVWire, 21 Sept. 2026, kevwire.com/record/project-zero-windows-dangling-com-aeff1dc7e91a.

Chicago

KEVWire. "Windows Exploitation Techniques: Dangling COM Object Registrations." Last modified September 21, 2026. https://kevwire.com/record/project-zero-windows-dangling-com-aeff1dc7e91a.

Evidence summary (plain text)

Windows Exploitation Techniques: Dangling COM Object Registrations (Sep 21, 2026).
This short blog post is about abusing a privilege escalation bug that Microsoft recently fixed in Windows, CVE-2026-66804, that I and 14 others reported. This issue is an incomplete fix for CVE-2026-50343, a bug dubbed “Dark Elevator” by Calif. The root cause of the bug was a dangling COM object registration for the CrossDevice COM object with the CLSID {E9F83CF2-E0C0-4CA7-AF01-E90C70BEF496}. A COM registration typically needs two parts: a server executable, which for in-process components is a DLL and a CLSID entry under the HKEY_CLASSES_ROOT registry key which points to that DLL.
Sources:
Google Project Zero Research: Windows Exploitation Techniques: Dangling COM Object Registrations: https://projectzero.google/2026/09/windows-dangling-com.html
Google Project Zero Research syndication feed: https://projectzero.google/feed.xml
Record ID: project-zero-windows-dangling-com-aeff1dc7e91a.
Record origin: Ingested record.
AI evidence: Not assessed.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 02:35 UTC. Ingestion is not an independent editorial investigation.

This is an excerpt of official research, not a reproduced result or evidence of exposure to a scored vulnerability.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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