Windows Exploitation Techniques: Dangling COM Object Registrations
B Project Zero · · CVE-2026-66804 , CVE-2026-50343
Admiralty grading (A–F · 1–6)
Source reliability
- A Completely reliable
- B Usually reliable
- C Fairly reliable
- D Not usually reliable
- E Unreliable
- F Cannot be judged
Information credibility
- 1 Confirmed
- 2 Probably true
- 3 Possibly true
- 4 Doubtful
- 5 Improbable
- 6 Cannot be judged
NATO Admiralty (AJP-2.1) grades confidence, independent of the risk score. Cross-source corroboration isn't tracked for non-CVE news, so single-source items are capped at a lower credibility number; a low number does not imply low quality.
Key metrics
- CVSS
- 7.8
- EPSS
- 0%
Affected versions
Key insight
Project Zero publishes a working exploit for an incompletely patched Windows LPE vulnerability already known as 'Dark Elevator'.
Description
The vulnerability involves a dangling COM object registration for the CrossDevice object with CLSID {E9F83CF2-E0C0-4CA7-AF01-E90C70BEF496}, where the corresponding server executable is missing. This allows attackers with local user privileges to pass a fake marshaled object reference to the ICreateObject interface and thereby execute privileged code in a system-wide process. CVE-2026-66804 is an incomplete fix for CVE-2026-50343 (dubbed 'Dark Elevator'), which originally exploited weak registry key permissions. A working exploit was publicly attached to the original issue tracker. Unpatched Windows systems where the CrossDevice class is registered system-wide are affected.
Risk score
- cvss base
- 78.00
- kev bonus
- 0.00
- epss bonus
- 0.00
- poc bonus
- 15.00
- raw before weight
- 93.00
- industry weight
- 1.21
- freshness factor
- 0.50
- exploitability factor
- 1.00
- days old
- 47.00
- vendor mismatch penalty
- 0.00
Path: operational