Nightmare-Eclipse just dropped "LegacyHive," a new Windows privilege-escalation zero-day PoC that targets the Windows User Profile Service, the component that loads a user's settings during sign-in (git.projectnightcrawler.dev)
from beep@piefed.world to cybersecurity@infosec.pub on 15 Jul 10:55
https://piefed.world/c/cybersecurity/p/1263200/nightmare-eclipse-just-dropped-legacyhive-a-new-windows-privilege-escalation-zero-day-po

cross-posted from: piefed.world/…/nightmare-eclipse-just-dropped-leg…

Announcement.

The PoC reportedly uses a carefully timed path-switching trick to make Windows mount another user’s Registry file, potentially an administrator’s, under a standard “helper” account.

Nightmare-Eclipse claims it works across supported Windows desktop and server builds patched through July 2026.

Nightmare-Eclipse says a private version could load arbitrary Registry hives, but that broader version has not been published.

Interestingly, Nightmare-Eclipse previously told us that vulnerability names are inspired by random events in his life. “LegacyHive” appears to break from that convention.

Deja vu: Microsoft patched this broad ProfSvc trust-boundary failure in 2015 as CVE-2015-0004, which also loaded another user’s hive. LegacyHive appears to use a new path-swap to revive that bug class.

As of writing: no CVE, no Microsoft advisory, no comment.

Text source: International Cyber Digest.

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