MiniPlasma Windows 0-Day Enables SYSTEM Privilege Escalation on Fully Patched Systems
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-17103 | Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability NVD description · AI analysis pending | 7.0 | 27% |
| — | ||
| CVE-2025-62221 | Use-After-Free Local Privilege Escalation in Windows Cloud Files Mini Filter Driver CVE-2025-62221 is a use-after-free flaw (CWE-416) in the Windows Cloud Files Mini Filter Driver, the in-box kernel component that handles cloud storage placeholder files. An attacker who already has low-privileged access on a local machine can trigger the flaw through operations involving the affected driver, with no user interaction required. Successful exploitation elevates the attacker's privileges on the local host, with high impact on confidentiality, integrity, and availability (CVSS 7.8), meaning effective full compromise of the machine. All listed Windows 10, Windows 11, and Windows Server builds are affected, and Microsoft shipped fixes in its December 2025 Patch Tuesday releases. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-12-09, indicating exploitation in the wild; EPSS is 2.5% (84th percentile) and no public proof-of-concept is known. Do: Deploy Microsoft's December 2025 Patch Tuesday cumulative updates (released on or around 2025-12-09) for each affected Windows 10, Windows 11, and Windows Server build via Windows Update, WSUS, or Intune, and confirm the update installed before treating hosts as remediated. Prioritize this patch given active exploitation and KEV status (federal agencies must follow BOD 22-01 timelines or the vendor's mitigations); no standalone workaround or public PoC is documented. Because this is a local privilege escalation, roll out first to fleets where low-privileged users routinely execute code, such as workstations and terminal/RDS servers. | 7.8 | 3% | KEV |
| masshundreds of millions to over 1 billion Windows 10/11 and Windows Server installations |
Full article307 words · extracted from thehackernews.com · click to collapse
Ravie LakshmananMay 18, 2026Zero Day / Vulnerability
Chaotic Eclipse, the security researcher behind the recently disclosed Windows flaws, YellowKey and GreenPlasma, has released a proof-of-concept (PoC) for a Windows privilege escalation zero-day flaw that grants attackers SYSTEM privileges on fully patched Windows systems.
Codenamed MiniPlasma, the vulnerability impacts "cldflt.sys," which refers to the Windows Cloud Files Mini Filter Driver, and resides in a routine named "HsmOsBlockPlaceholderAccess." It was originally reported to Microsoft by Google Project Zero researcher James Forshaw in September 2020.
Although it was assumed that the shortcoming was fixed by Microsoft in December 2020 as part of CVE-2020-17103, Chaotic Eclipse said further investigation has uncovered that the "exact same issue [...] is actually still present, unpatched."
"I'm unsure if Microsoft just never patched the issue or the patch was silently rolled back at some point for unknown reasons. The original PoC by Google worked without any changes," the researcher added. "To highlight this issue, I weaponized the original PoC to spawn a SYSTEM shell. It seems to work reliably in my machines butsuccess rate may vary since it's a race condition."
The researcher further pointed out that all Windows versions are likely affected by this vulnerability.
In a post shared on Mastodon, security researcher Will Dormann said MiniPlasma works "reliably" to open a "cmd.exe" prompt with SYSTEM privileges on Windows 11 systems running the latest May 2026 updates. "I'll note that it does not seem to work on the latest Insider Preview Canary Windows 11," Dormann pointed out.
In December 2025, Microsoft also addressed another privilege escalation flaw in the same component (CVE-2025-62221, CVSS score: 7.8), which it identified as exploited by unknown threat actors.
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