Experts published unpatched Windows zero-day BlueHammer
Experts published unpatched Windows zero-day BlueHammer
Publish Date: 2026-04-07 04:09:00
Source Domain: securityaffairs.com
Experts published unpatched Windows zero-day BlueHammer
Pierluigi Paganini
April 07, 2026
A researcher leaked the unpatched Windows zero-day “BlueHammer,” letting attackers gain SYSTEM rights; no patch exists yet.
A disgruntled researcher released the BlueHammer Windows zero-day, a privilege escalation flaw that allows attackers to gain SYSTEM or admin rights, Bleeping Computer reports.
The researcher privately reported the vulnerability to Microsoft but criticized the way the Microsoft’s Security Response Center (MSRC) managed the disclosure process. On April 3rd, the expert published the BlueHammer exploit on GitHub under the alias Nightmare-Eclipse. Microsoft hasn’t released a patch, so the flaw qualifies as a zero-day and leaves Windows systems open to potential attacks.
“I’m just really wondering what was the math behind their decision, like you knew this was going to happen and you still did whatever you did ? Are they serious ?” reads the description published in the Github repository hosting the BlueHammer vulnerability.
Frustrated nerd drops zero day exploit after Microsoft vulnerability bug bounty people annoy him, or something, I don’t know.
I haven’t tested or confirmed, but stinky nerds tell me it’s legit. https://t.co/u19Dy2SP0k
— vx-underground (@vxunderground) April 6, 2026
Nightmare-Eclipse pointed out that he inserted a few bugs in the PoC exploit code that could prevent it from working.
Popular cybersecurity experts Will Dormann confirmed that the BlueHammer exploit works. It’s a local privilege escalation (LPE) flaw combining TOCTOU and path confusion. The exploitation is not easy, however it can let a local attacker access the Security Account Manager (SAM) database with password hashes. With this access, attackers can escalate to SYSTEM privileges, potentially fully compromising the machine and spawning SYSTEM-level shells to control the…
