Microsoft Exchange Server vulnerabilities: known CVEs & security history
Microsoft · Microsoft · 245 tracked CVEs · 20 actively exploited · updated June 2026 · what is a CVE? →
This is the full list of known vulnerabilities (CVEs) across all Microsoft Exchange Server release lines — 245 in total, with 20 actively exploited in the wild. A CVE here doesn't mean your version is affected — check Microsoft Exchange Server's current status and the safe version to run.
Known Microsoft Exchange Server CVEs
Actively-exploited and most-severe first. Showing the top 80 of 245. Open any CVE for full details.
| CVE | Severity | CVSS | EPSS | Year |
|---|---|---|---|---|
| CVE-2024-21410⚡ exploited | critical | 9.8 | 13% | 2024 |
| CVE-2021-34473⚡ exploited | critical | 9.1 | 100% | 2021 |
| CVE-2021-26855⚡ exploited | critical | 9.1 | 100% | 2021 |
| CVE-2021-34523⚡ exploited | critical | 9 | 100% | 2021 |
| CVE-2023-21529⚡ exploited | high | 8.8 | 62% | 2023 |
| CVE-2022-41080⚡ exploited | high | 8.8 | 77% | 2022 |
| CVE-2022-41040⚡ exploited | high | 8.8 | 100% | 2022 |
| CVE-2021-42321⚡ exploited | high | 8.8 | 90% | 2021 |
| CVE-2020-0688⚡ exploited | high | 8.8 | 100% | 2020 |
| CVE-2020-17144⚡ exploited | high | 8.4 | 37% | 2020 |
| CVE-2026-42897⚡ exploited | high | 8.1 | 3% | 2026 |
| CVE-2022-41082⚡ exploited | high | 8 | 100% | 2022 |
| CVE-2021-27065⚡ exploited | high | 7.8 | 100% | 2021 |
| CVE-2021-26858⚡ exploited | high | 7.8 | 90% | 2021 |
| CVE-2021-26857⚡ exploited | high | 7.8 | 94% | 2021 |
| CVE-2017-8540⚡ exploited | high | 7.8 | 72% | 2017 |
| CVE-2018-8581⚡ exploited | high | 7.4 | 28% | 2018 |
| CVE-2021-33766⚡ exploited | high | 7.3 | 98% | 2021 |
| CVE-2021-31196⚡ exploited | high | 7.2 | 46% | 2021 |
| CVE-2021-31207⚡ exploited | medium | 6.6 | 100% | 2021 |
| CVE-2023-21709 | critical | 9.8 | 2% | 2023 |
| CVE-2021-28481 | critical | 9.8 | 36% | 2021 |
| CVE-2021-28480 | critical | 9.8 | 71% | 2021 |
| CVE-2019-1373 | critical | 9.8 | 18% | 2019 |
| CVE-2019-0586 | critical | 9.8 | 15% | 2019 |
| CVE-2018-8302 | critical | 9.8 | 26% | 2018 |
| CVE-2018-8154 | critical | 9.8 | 22% | 2018 |
| CVE-2021-27078 | critical | 9.1 | 18% | 2021 |
| CVE-2021-26412 | critical | 9.1 | 30% | 2021 |
| CVE-2020-17142 | critical | 9.1 | 3% | 2020 |
| CVE-2020-17132 | critical | 9.1 | 90% | 2020 |
| CVE-2022-21969 | critical | 9 | 1% | 2022 |
| CVE-2022-21855 | critical | 9 | 1% | 2022 |
| CVE-2022-21846 | critical | 9 | 1% | 2022 |
| CVE-2021-26427 | critical | 9 | 1% | 2021 |
| CVE-2021-28483 | critical | 9 | 1% | 2021 |
| CVE-2007-0213 | high | 10 | 66% | 2007 |
| CVE-2004-0574 | high | 10 | 68% | 2004 |
| CVE-2004-0840 | high | 10 | 30% | 2004 |
| CVE-1999-0385 | high | 10 | 18% | 1998 |
| CVE-2009-1491 | high | 9.3 | 3% | 2009 |
| CVE-2009-0098 | high | 9.3 | 25% | 2009 |
| CVE-2026-45504 | high | 8.8 | 0% | 2026 |
| CVE-2025-59249 | high | 8.8 | 1% | 2025 |
| CVE-2024-26198 | high | 8.8 | 7% | 2024 |
| CVE-2023-38185 | high | 8.8 | 3% | 2023 |
| CVE-2023-38181 | high | 8.8 | 17% | 2023 |
| CVE-2023-35368 | high | 8.8 | 4% | 2023 |
| CVE-2023-32031 | high | 8.8 | 82% | 2023 |
| CVE-2023-21707 | high | 8.8 | 82% | 2023 |
| CVE-2023-21706 | high | 8.8 | 4% | 2023 |
| CVE-2022-23277 | high | 8.8 | 43% | 2022 |
| CVE-2021-28482 | high | 8.8 | 83% | 2021 |
| CVE-2020-17143 | high | 8.8 | 71% | 2020 |
| CVE-2018-0986 | high | 8.8 | 61% | 2018 |
| CVE-2018-16793 | high | 8.6 | 11% | 2018 |
| CVE-2020-17084 | high | 8.5 | 4% | 2020 |
| CVE-2025-53782 | high | 8.4 | 0% | 2025 |
| CVE-2020-17141 | high | 8.4 | 7% | 2020 |
| CVE-2020-16875 | high | 8.4 | 47% | 2020 |
| CVE-2022-21978 | high | 8.2 | 1% | 2022 |
| CVE-2026-47631 | high | 8.1 | 0% | 2026 |
| CVE-2026-45503 | high | 8.1 | 0% | 2026 |
| CVE-2020-0692 | high | 8.1 | 3% | 2020 |
| CVE-2019-1136 | high | 8.1 | 3% | 2019 |
| CVE-2019-0724 | high | 8.1 | 24% | 2019 |
| CVE-2017-11932 | high | 8.1 | 6% | 2017 |
| CVE-2025-53786 | high | 8 | 7% | 2025 |
| CVE-2023-36439 | high | 8 | 5% | 2023 |
| CVE-2023-36050 | high | 8 | 39% | 2023 |
| CVE-2023-36039 | high | 8 | 73% | 2023 |
| CVE-2023-36035 | high | 8 | 87% | 2023 |
| CVE-2023-36778 | high | 8 | 4% | 2023 |
| CVE-2023-36757 | high | 8 | 69% | 2023 |
| CVE-2023-36756 | high | 8 | 75% | 2023 |
| CVE-2023-36745 | high | 8 | 81% | 2023 |
| CVE-2023-36744 | high | 8 | 82% | 2023 |
| CVE-2023-38182 | high | 8 | 11% | 2023 |
| CVE-2023-35388 | high | 8 | 12% | 2023 |
| CVE-2023-28310 | high | 8 | 25% | 2023 |
165 older / lower-severity CVEs not shown — see Microsoft Exchange Server's full record.
Is my Microsoft Exchange Server 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 Exchange Server version → · Monitor Microsoft Exchange Server for new CVEs →
Microsoft Exchange Server vulnerabilities — frequently asked
How many known vulnerabilities does Microsoft Exchange Server have?
IsItPatched tracks 245 CVEs for Microsoft Exchange Server, 20 of which are actively exploited (CISA KEV). 20 are critical-severity and 106 high-severity. These span every release line — what matters is whether the version you run is affected.
Does Microsoft Exchange Server have any actively-exploited vulnerabilities?
Yes — 20 Microsoft Exchange Server CVEs are in CISA's Known Exploited Vulnerabilities catalog, meaning they are confirmed exploited in the wild (14 linked to ransomware). Patch these as a priority.
What is the most severe Microsoft Exchange Server vulnerability?
Among tracked issues, CVE-2024-21410 (CRITICAL, CVSS 9.8), which is actively exploited, ranks highest — a Improper authentication weakness.
Is Microsoft Exchange Server safe to use?
It depends on the version. The latest supported Microsoft Exchange Server release (15.2.2562.43) 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 Exchange Server security status · Microsoft Exchange Server end-of-life · actively-exploited CVEs. Always verify against Microsoft's advisories — see our disclaimer.