Dude is on a roll
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github.com
TLDR: You can easily gain admin access from a standard account.
A cybersecurity researcher has released a proof-of-concept exploit for a Windows privilege escalation zero-day dubbed "MiniPlasma" that lets attackers gain SYSTEM privileges on fully patched Windows systems.
The exploit was published by a researcher known as Chaotic Eclipse, or Nightmare Eclipse, who released both the source code and a compiled executable on GitHub after claiming that Microsoft failed to properly patch a previously reported 2020 vulnerability.
According to the researcher, the flaw impacts the 'cldflt.sys' Cloud Filter driver and its 'HsmOsBlockPlaceholderAccess' routine, which was originally reported to Microsoft by Google Project Zero researcher James Forshaw in September 2020.
At the time, the flaw was assigned the CVE-2020-17103 identifier and reportedly fixed in December 2020.
"After investigating, it turns out the exact same issue that was reported to Microsoft by Google project zero is actually still present, unpatched," explains Chaotic Eclipse.
"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."
BleepingComputer tested the exploit on a fully patched Windows 11 Pro system running the latest May 2026 Patch Tuesday updates.
In our test, we used a standard user account, and after running the exploit, it opened a command prompt with SYSTEM privileges, as shown in the image below.
MiniPlasma exploit successfully gave Windows SYSTEM privileges
Source: BleepingComputer
Will Dormann, principal vulnerability analyst at Tharros, also confirmed the exploit works in his tests on the latest public version of Windows 11. However, he said that the flaw does not work in the latest Windows 11 Insider Preview Canary build.
The exploit appears to abuse how the Windows Cloud Filter driver handles registry key creation through an undocumented CfAbortHydration API. Forshaw's original report said that the flaw could allow arbitrary registry keys to be created in the .DEFAULT user hive without proper access checks, potentially enabling privilege escalation.
While Microsoft reports having fixed the bug as part of its December 2020 Microsoft Patch Tuesday, Chaotic Eclipse now claims the vulnerability can still be exploited.
BleepingComputer contacted Microsoft about this additional zero-day and will update this story if we receive a response.
The disclosure spree began in April with BlueHammer, a Windows local privilege escalation flaw tracked as CVE-2026-33825, followed by another privilege escalation vulnerability, RedSun, and a Windows Defender DoS tool, UnDefend.
After their disclosure, all three vulnerabilities were spotted being exploited in attacks. According to the researcher, Microsoft silently patched the RedSun issue without assigning it a CVE identifier.
This month, the researcher also released two additional exploits named YellowKey and GreenPlasma.
YellowKey is a BitLocker bypass affecting Windows 11 and Windows Server 2022/2025 that spawns a command shell that gives access to unlocked drives protected by TPM-only BitLocker configurations.
MiniPlasma Windows 0-Day Enables SYSTEM Privilege Escalation on Fully Patched Systems
New Windows 'MiniPlasma' zero-day exploit gives SYSTEM access, PoC released
A cybersecurity researcher has released a proof-of-concept exploit for a Windows privilege escalation zero-day dubbed "MiniPlasma" that lets attackers gain SYSTEM privileges on fully patched Windows systems.
GitHub - Nightmare-Eclipse/MiniPlasma: CVE-2020-17103 was apparently not patched or the patch was reversed, regardless this the PoC for an LPE in cldflt.sys
CVE-2020-17103 was apparently not patched or the patch was reversed, regardless this the PoC for an LPE in cldflt.sys - Nightmare-Eclipse/MiniPlasma
github.com
TLDR: You can easily gain admin access from a standard account.
A cybersecurity researcher has released a proof-of-concept exploit for a Windows privilege escalation zero-day dubbed "MiniPlasma" that lets attackers gain SYSTEM privileges on fully patched Windows systems.
The exploit was published by a researcher known as Chaotic Eclipse, or Nightmare Eclipse, who released both the source code and a compiled executable on GitHub after claiming that Microsoft failed to properly patch a previously reported 2020 vulnerability.
According to the researcher, the flaw impacts the 'cldflt.sys' Cloud Filter driver and its 'HsmOsBlockPlaceholderAccess' routine, which was originally reported to Microsoft by Google Project Zero researcher James Forshaw in September 2020.
At the time, the flaw was assigned the CVE-2020-17103 identifier and reportedly fixed in December 2020.
"After investigating, it turns out the exact same issue that was reported to Microsoft by Google project zero is actually still present, unpatched," explains Chaotic Eclipse.
"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."
BleepingComputer tested the exploit on a fully patched Windows 11 Pro system running the latest May 2026 Patch Tuesday updates.
In our test, we used a standard user account, and after running the exploit, it opened a command prompt with SYSTEM privileges, as shown in the image below.
Source: BleepingComputer
Will Dormann, principal vulnerability analyst at Tharros, also confirmed the exploit works in his tests on the latest public version of Windows 11. However, he said that the flaw does not work in the latest Windows 11 Insider Preview Canary build.
The exploit appears to abuse how the Windows Cloud Filter driver handles registry key creation through an undocumented CfAbortHydration API. Forshaw's original report said that the flaw could allow arbitrary registry keys to be created in the .DEFAULT user hive without proper access checks, potentially enabling privilege escalation.
While Microsoft reports having fixed the bug as part of its December 2020 Microsoft Patch Tuesday, Chaotic Eclipse now claims the vulnerability can still be exploited.
BleepingComputer contacted Microsoft about this additional zero-day and will update this story if we receive a response.
Researcher behind the recent string of Windows zero-days
MiniPlasma is the latest in a string of Windows zero-day disclosures published by the researcher over the past several weeks.The disclosure spree began in April with BlueHammer, a Windows local privilege escalation flaw tracked as CVE-2026-33825, followed by another privilege escalation vulnerability, RedSun, and a Windows Defender DoS tool, UnDefend.
After their disclosure, all three vulnerabilities were spotted being exploited in attacks. According to the researcher, Microsoft silently patched the RedSun issue without assigning it a CVE identifier.
This month, the researcher also released two additional exploits named YellowKey and GreenPlasma.
YellowKey is a BitLocker bypass affecting Windows 11 and Windows Server 2022/2025 that spawns a command shell that gives access to unlocked drives protected by TPM-only BitLocker configurations.
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