---
id: "CVE-2020-0601"
kind: "vulnerability"
aliases: ["CVE-2020-0601"]
title: "Microsoft Windows: Microsoft Windows CryptoAPI Spoofing Vulnerability"
severity: "high"
cvss: 8.1
epss: 0.89436
exploited: true
status: "open"
category: "vendor"
products: [{"name": "Microsoft Windows", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["code-signing", "exploited", "tls", "vendor", "windows", "windows-server"]
not_affected_if: ["patched-windows"]
published_at: "2020-01-14T23:15:30+00:00"
first_seen_at: "2026-10-23T19:11:53+00:00"
updated_at: "2026-10-23T21:57:34+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-0601", "first_seen_at": "2026-10-23T19:11:53+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2020-0601", "first_seen_at": "2026-10-23T19:13:44+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-0601", "first_seen_at": "2026-10-23T21:57:34+00:00"}]
---

# Microsoft Windows: Microsoft Windows CryptoAPI Spoofing Vulnerability

Windows CryptoAPI (Crypt32.dll) incorrectly validates ECC certificates, so a forged certificate passes as trusted. An attacker can sign malware so it looks like it came from a legitimate publisher, or intercept and decrypt connections that rely on the bad check.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Microsoft Windows affected ? fixed ?

## Fix

Apply the Microsoft security update for CVE-2020-0601 per vendor instructions (CISA KEV required action).

## Timeline

- 2026-10-23T19:11:53+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-0601
- 2026-10-23T19:13:44+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2020-0601
- 2026-10-23T21:57:34+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2020-0601

## From the sources

Microsoft Windows CryptoAPI (Crypt32.dll) contains a spoofing vulnerability in the way it validates Elliptic Curve Cryptography (ECC) certificates. An attacker could exploit the vulnerability by using a spoofed code-signing certificate to sign a malicious executable, making it appear the file was from a trusted, legitimate source. A successful exploit could also allow the attacker to conduct man-in-the-middle attacks and decrypt confidential information on user connections to the affected software. The vulnerability is also known under the moniker of CurveBall.

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_