Microsoft Exchange Server ↗
On-premises Exchange Server only. Exchange Online (Microsoft 365) is a cloud service patched by Microsoft and is not covered here.
Summary iPlain-English security verdict for Microsoft Exchange Server, generated from its current health score, actively-exploited vulnerabilities, and latest supported version.
Microsoft Exchange Server currently scores 35/100 — high risk. 11 of its known vulnerabilities are being actively exploited in the wild (CISA KEV), including CVE-2021-34473. The latest supported release is 15.2.2562.46. Upgrade soon — serious vulnerabilities are open and a fix usually exists. Note: this product is assessed at the product level on recent (365-day) activity rather than an exact per-version match, so it is never marked a confident "healthy".
Disclosure trend iNew CVEs published for Microsoft Exchange Server each year (NVD). A higher bar means more disclosures that year — more scrutiny, not necessarily less safe.
9 of its known vulnerabilities are linked to ransomware campaigns (CISA KEV).
Patch priority — what to act on iThe issues to fix first — actively exploited (CISA KEV) first, then by exploitation probability (EPSS), then severity. Each row's "→ fixed in" is the earliest version that patches it; "see advisory" means no fixed version is published.
Most urgent first — actively exploited, then likeliest to be exploited.
CVE-2021-34473 CRITICAL exploited ransomware Server-side request forgery (SSRF) EPSS 100% → see advisory CVE-2021-26855 CRITICAL exploited ransomware Server-side request forgery (SSRF) EPSS 100% → see advisory CVE-2021-34523 CRITICAL exploited ransomware EPSS 100% → see advisory CVE-2021-27065 HIGH exploited ransomware Path traversal EPSS 100% → see advisory CVE-2021-33766 HIGH exploited EPSS 98% → see advisory CVE-2021-26857 HIGH exploited ransomware Insecure deserialization EPSS 94% → see advisory CVE-2021-42321 HIGH exploited ransomware EPSS 90% → see advisory CVE-2021-26858 HIGH exploited ransomware EPSS 90% → see advisory CVE-2022-41080 HIGH exploited ransomware EPSS 77% → see advisory CVE-2023-21529 HIGH exploited ransomware Insecure deserialization EPSS 62% → see advisory CVE-2021-31196 HIGH exploited EPSS 46% → see advisory CVE-2021-41349 MEDIUM EPSS 94% → see advisorySee all 48 known Microsoft Exchange Server CVEs & security history →
How to patch Microsoft Exchange Server — step-by-step to the latest secure version →
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Versions & lifecycle iWhen each release line stops receiving security patches (end-of-life). After EOL there are no more fixes — plan upgrades before these dates.
How long each Microsoft Exchange Server release line is supported — and when it sunsets.
Full Microsoft Exchange Server end-of-life dates & support timeline →
Frequently asked
Is Microsoft Exchange Server safe and patched?
Microsoft Exchange Server currently scores 35/100 — high risk. 11 of its known vulnerabilities are being actively exploited in the wild (CISA KEV), including CVE-2021-34473. The latest supported release is 15.2.2562.46. Upgrade soon — serious vulnerabilities are open and a fix usually exists. Note: this product is assessed at the product level on recent (365-day) activity rather than an exact per-version match, so it is never marked a confident "healthy".
What should I do about Microsoft Exchange Server now?
Upgrade Microsoft Exchange Server to the latest supported release (15.2.2562.46) or later, which clears the actively-exploited issues affecting older versions, then confirm against Microsoft's official advisory.
When does Microsoft Exchange Server reach end-of-life?
The latest supported Microsoft Exchange Server release is 15.2.2562.46. After end-of-life a release no longer receives security patches.
Which versions of Microsoft Exchange Server are still receiving security updates?
Supported Microsoft Exchange Server release lines (latest 15.2.2562.46): subscription. End-of-life releases no longer receive security patches.
product-level posture (last 365d); exact per-version verdict pending precise version mapping
Informational only, from public data (NVD · CISA KEV · EPSS · endoflife.date), and can lag or miss vendor-specific fixes. Always confirm against Microsoft's official advisory before you patch or upgrade — Microsoft Exchange Server official site ↗