CurveBall (CVE-2020-0601)
Microsoft Windows CryptoAPI Spoofing Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.
Required action
Apply updates per vendor instructions.
CISA 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
Also Known as CurveBall
CurveBall is the name used for a Windows CryptoAPI (crypt32.dll) flaw in validating elliptic curve certificates, which allows certificate spoofing. The NSA discovered and reported it, and Microsoft patched it in January 2020.
Other names: Chain of Fools
Description
A spoofing vulnerability exists in the way Windows CryptoAPI (Crypt32.dll) 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, aka 'Windows CryptoAPI Spoofing Vulnerability'.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:NExploitation Context
as of October 14, 2026- CISA added CVE-2020-0601 to the KEV catalog 659 days after its CVE record was published.
- It is one of 391 Microsoft entries in the CISA KEV catalog, and one of 83 added in 2021.
- Its current EPSS score (89.4%) is higher than that of 72% of CISA KEV entries.
Affected Products
| Vendor | Product | Affected versions |
|---|---|---|
| Microsoft | Microsoft Windows | 10 Version 1803 for 32-bit Systems 10 Version 1803 for x64-based Systems 10 Version 1803 for ARM64-based Systems 10 Version 1809 for 32-bit Systems 10 Version 1809 for x64-based Systems 10 Version 1809 for ARM64-based Systems 10 Version 1709 for 32-bit Systems 10 Version 1709 for x64-based Systems 10 Version 1709 for ARM64-based Systems 10 for 32-bit Systems 10 for x64-based Systems 10 Version 1607 for 32-bit Systems 10 Version 1607 for x64-based Systems |
| Microsoft | Microsoft Windows Server | version 1803 (Core Installation) 2019 2019 (Core installation) 2016 2016 (Core installation) |
| Microsoft | Microsoft Windows 10 Version 1903 for 32-bit Systems | unspecified |
| Microsoft | Microsoft Windows 10 Version 1903 for x64-based Systems | unspecified |
| Microsoft | Microsoft Windows 10 Version 1903 for ARM64-based Systems | unspecified |
| Microsoft | Microsoft Windows Server, version 1903 (Server Core installation) | unspecified |
| Microsoft | Microsoft Windows 10 Version 1909 for 32-bit Systems | unspecified |
| Microsoft | Microsoft Windows 10 Version 1909 for x64-based Systems | unspecified |
| Microsoft | Microsoft Windows Server, version 1909 (Server Core installation) | unspecified |
| Microsoft | Microsoft Windows 10 Version 1909 for ARM64-based Systems | unspecified |
References
3 Links- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0601
- http://packetstormsecurity.com/files/155961/CurveBall-Microsoft-Windows-CryptoAPI-Spoofing-Proof-Of-Concept.html
- http://packetstormsecurity.com/files/155960/CurveBall-Microsoft-Windows-CryptoAPI-Spoofing-Proof-Of-Concept.html
Record Details
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CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.