CVSS base score: 10.0 (Critical) CISA · v3.1
Score assigned by CISA's Vulnrichment program; the vendor's CVE record did not include one.
Microsoft Windows DNS Server Remote Code Execution Vulnerability
Vendor: Microsoft Product: Windows
Microsoft Windows DNS Servers fail to properly handle requests, allowing an attacker to perform remote code execution in the context of the Local System Account. The vulnerability is also known under the moniker of SIGRed.
Each milestone comes from a different source, so gaps between them are gaps in what those sources publish, not evidence that nothing happened. EPSS history for this CVE holds 262 points from 2021-12-11, tracked daily from 2026-09-09; earlier points are weekly, which dates a spike to within a week. Peak probability 94.6% on 2024-08-24.
Check whether a specific version is affected →
What each source publishes about which product versions carry this vulnerability, kept as written rather than merged. Absence here means no source has published applicability data, not that nothing is affected.
No mentions found in monitored research blogs or news feeds.
Coverage across public collections only: Nuclei and OpenVAS NVT (scan);
Snort and Suricata ET Open (network); Sigma and YARA (host/SIEM);
Metasploit, Exploit-DB and public GitHub repositories (exploit). Absence
here means nothing public was found, not that detection is impossible.
GitHub PoC repositories are collected automatically by
PoC-in-GitHub (CC0) and are not vetted:
some are fakes and some are malware. Treat them as evidence that code was
published, not as code to run.
OpenVAS coverage derives from the Greenbone Community Feed, made available
under the Open Database License (ODbL) v1.0;
its individual Vulnerability Tests are licensed
GNU GPL v2.
Windows DNS Server Remote Code Execution Vulnerability
The vendor's own judgement about their own code, shown alongside CISA's rather than merged into it. The exploitability index is a forward-looking prediction, distinct from a CVSS severity or CISA's SSVC decision, and vendors often report observed exploitation before a CVE reaches the KEV catalog. Vendor advisory →
Defensive techniques inferred by MITRE D3FEND from the underlying weakness (CWE-20) — general hardening and detection guidance for this weakness class, not a vendor patch for this specific CVE.
| Source | Date | Record |
|---|---|---|
| CISA KEV | 2021-11-03 | source record → |
| CISA Vulnrichment | 2025-02-07 | source record → |
No exploit-tool sightings recorded for this CVE.
Evidence tiers are explained on the About page — a merged Metasploit module is far stronger evidence than a distro package mention.