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Known exploited vulnerability · CISA KEV

CVE-2017-8540: Microsoft Malware Protection Engine Improper Restriction of Operations Vulnerability

The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016, Microsoft Exchange Server 2013 and 2016, does not properly scan a specially crafted file leading to memory corruption. aka "Microsoft Malware Protection Engine Remote Code Execution Vulnerability".

CVE-2017-8540

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2022-03-03: attackers are using it right now.

CISA KEV
Listed
Added 2022-03-03 · federal fix-by 2022-03-24
EPSS (30 days)
72%
Higher than 99.4% of CVEs · 2026-11-01
CVSS
No score

What CISA says

Microsoft Malware Protection Engine Improper Restriction of Operations Vulnerability

Apply updates per vendor instructions.

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How to check if you are exposed to CVE-2017-8540

  1. Find every Microsoft Malware Protection Engine system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2017-8540.

US federal agencies had to fix this by 2022-03-24. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Timeline

  1. · Added to CISA's Known Exploited Vulnerabilities catalog
  2. · Fix-by date for US federal agencies, passed 1,683 days ago

Weakness type

More exploited Microsoft vulnerabilities

CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:

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Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

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