Microsoft Windows CryptoAPI Spoofing Vulnerability
Microsoft / Windows
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.
- CVE identifier
- CVE-2020-0601
- Added to KEV
- Nov 3, 2021
- CISA catalog dueDate
- May 3, 2022
The dates above are catalog fields. The addition date does not establish when the vulnerability was discovered or first exploited. Confirm which requirements apply to your organisation separately.
Publisher's required action
Apply updates per vendor instructions.
This wording is attributed to the CISA snapshot. Verify current vendor guidance, affected versions and your deployment before applying changes.
Keep the signals separate.
- Ransomware use, as reported by CISA
- Unknown
- CVSS severity
- Not supplied by KEV
- EPSS probability
- 89.44%
EPSS score date: 2026-09-27T12:00:21Z. Percentile: 99.78%. Model version: v2026.06.15.
A dated estimate of exploitation probability over the following 30 days, not a severity score or a probability of a breach in your environment.
Inspect the EPSS source ↗“Unknown” ransomware use is an unknown source field, not proof that ransomware activity has not occurred.
Source notes
Reference CISA's ED 20-02 (https://www.cisa.gov/news-events/directives/ed-20-02-mitigate-windows-vulnerabilities-january-2020-patch-tuesday) for further guidance and requirements. Note: The due date for addressing this vulnerability aligns with the requirements outlined in ED 20-02. https://nvd.nist.gov/vuln/detail/CVE-2020-0601
Source & freshness
Source updated: Sep 27, 2026, 9:30 PM UTC
Successfully checked: Sep 27, 2026, 11:50 PM UTC
This snapshot is older than 36 hours. Check current publisher guidance.
Automated source record, not an editorial advisory or an independent discovery. No affected or fixed version is inferred, and no organisation-specific risk rating is generated.