Microsoft Defender (Malware Protection Engine) vulnerabilities: known CVEs & security history
Microsoft · Endpoint security · 28 tracked CVEs · 2 actively exploited · updated June 2026 · what is a CVE? →
This is the full list of known vulnerabilities (CVEs) across all Microsoft Defender (Malware Protection Engine) release lines — 28 in total, with 2 actively exploited in the wild. A CVE here doesn't mean your version is affected — check Microsoft Defender (Malware Protection Engine)'s current status and the safe version to run.
Known Microsoft Defender (Malware Protection Engine) CVEs
Actively-exploited and most-severe first. Open any CVE for full details.
| CVE | Severity | CVSS | EPSS | Year |
|---|---|---|---|---|
| CVE-2026-41091⚡ exploited | high | 7.8 | 1% | 2026 |
| CVE-2017-8540⚡ exploited | high | 7.8 | 72% | 2017 |
| CVE-2013-1346 | high | 9.3 | 12% | 2013 |
| CVE-2006-5270 | high | 9.3 | 30% | 2007 |
| CVE-2026-45584 | high | 8.1 | 1% | 2026 |
| CVE-2026-50656 | high | 7.8 | 0% | 2026 |
| CVE-2021-42298 | high | 7.8 | 5% | 2021 |
| CVE-2021-34471 | high | 7.8 | 0% | 2021 |
| CVE-2021-34464 | high | 7.8 | 3% | 2021 |
| CVE-2021-34522 | high | 7.8 | 3% | 2021 |
| CVE-2021-31985 | high | 7.8 | 8% | 2021 |
| CVE-2017-11940 | high | 7.8 | 20% | 2017 |
| CVE-2017-11937 | high | 7.8 | 28% | 2017 |
| CVE-2017-8541 | high | 7.8 | 50% | 2017 |
| CVE-2017-8538 | high | 7.8 | 50% | 2017 |
| CVE-2017-0290 | high | 7.8 | 77% | 2017 |
| CVE-2023-24860 | high | 7.5 | 3% | 2023 |
| CVE-2011-0037 | high | 7.2 | 2% | 2011 |
| CVE-2022-37971 | high | 7.1 | 1% | 2022 |
| CVE-2023-33156 | medium | 6.3 | 0% | 2023 |
| CVE-2023-23389 | medium | 6.3 | 0% | 2023 |
| CVE-2022-24548 | medium | 5.5 | 3% | 2022 |
| CVE-2021-31978 | medium | 5.5 | 1% | 2021 |
| CVE-2017-8542 | medium | 5.5 | 6% | 2017 |
| CVE-2017-8539 | medium | 5.5 | 6% | 2017 |
| CVE-2008-1437 | medium | 5 | 13% | 2008 |
| CVE-2008-1438 | medium | 5 | 13% | 2008 |
| CVE-2014-2779 | medium | 4.3 | 13% | 2014 |
Is my Microsoft Defender (Malware Protection Engine) version affected?
The list above spans every release. To know whether your version is affected — and the minimum safe version to upgrade to — check it directly.
Check your Microsoft Defender (Malware Protection Engine) version → · Monitor Microsoft Defender (Malware Protection Engine) for new CVEs →
Microsoft Defender (Malware Protection Engine) vulnerabilities — frequently asked
How many known vulnerabilities does Microsoft Defender (Malware Protection Engine) have?
IsItPatched tracks 28 CVEs for Microsoft Defender (Malware Protection Engine), 2 of which are actively exploited (CISA KEV). 0 are critical-severity and 19 high-severity. These span every release line — what matters is whether the version you run is affected.
Does Microsoft Defender (Malware Protection Engine) have any actively-exploited vulnerabilities?
Yes — 2 Microsoft Defender (Malware Protection Engine) CVEs are in CISA's Known Exploited Vulnerabilities catalog, meaning they are confirmed exploited in the wild. Patch these as a priority.
What is the most severe Microsoft Defender (Malware Protection Engine) vulnerability?
Among tracked issues, CVE-2026-41091 (HIGH, CVSS 7.8), which is actively exploited, ranks highest — a CWE-59 weakness.
Is Microsoft Defender (Malware Protection Engine) safe to use?
It depends on the version. The latest supported Microsoft Defender (Malware Protection Engine) release clears the known issues; older versions may still be affected. Check the exact version you run for a verdict.
CVE data aggregated from NVD, CISA KEV and EPSS (FIRST.org). Related: Microsoft Defender (Malware Protection Engine) security status · Microsoft Defender (Malware Protection Engine) end-of-life · actively-exploited CVEs. Always verify against Microsoft's advisories — see our disclaimer.