Windows CLFS: SignDrop Zero-Day Exploit

Windows CLFS

Windows CLFS is affected by SignDrop Zero-Day Exploit, allowing local privilege escalation

Do this now

Check the vendor advisory for a fix and limit local user access on affected Windows systems meanwhile.

Who should check: teams running Windows

First seen: 12 Nov 2026
Last update: 13 Nov 2026, 09:17 UTC
Source: news
On the menu as: Windows

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Windows CLFS: SignDrop Zero-Day Exploit
Severity: unknown. Patch status: fix status unknown.
Affected: Windows CLFS

Windows CLFS is affected by SignDrop Zero-Day Exploit, allowing local privilege escalation

## Steps
1. This touches infrastructure (windows). Look in terraform, ansible, cloud-init, Dockerfiles and docs for the product and version we run. If it isn't in the repo, say so and list what a human should check on the box.
2. No source names a fix yet; check the vendor advisory. Until one ships: restrict network access to it.

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://thehackernews.com/2026/11/new-signdrop-zero-day-exploit-turns.html https://www.securityweek.com/nightmare-eclipse-drops-windows-zero-day-exploit-signdrop/ https://securityaffairs.com/202968/hacking/new-signdrop-exploit-can-abuse-windows-defender-to-bypass-security-protections.html
https://pwned.coffee/i/windows-clfs-signdrop-zero-day-exploit

Timeline

13 Nov 2026, 09:17 UTC
Reported by securityweek.com: Nightmare Eclipse Drops Windows Zero-Day Exploit ‘SignDrop’
12 Nov 2026, 18:19 UTC
Fix status: no fix yet → unknown.
12 Nov 2026
First reported.

Receipt

Exploitation: No known exploitation
Score: No CVSS published yet: severity unknown.
Last checked: 13 Nov 2026, 16:26 UTC

Sources: KEV – CVE record – Vendor –

Sources

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