CRITICAL 9.1 Microsoft PoC
CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability
Microsoft Security Update 2021-Mar: Microsoft Exchange Server Remote Code Execution Vulnerability
Affected Products
- Microsoft Exchange Server 2016 Cumulative Update 19
- Microsoft Exchange Server 2019 Cumulative Update 8
- Microsoft Exchange Server 2019
- Microsoft Exchange Server 2013 Cumulative Update 22
- Microsoft Exchange Server 2019 Cumulative Update 2
- Microsoft Exchange Server 2016 Cumulative Update 13
- Microsoft Exchange Server 2013 Cumulative Update 23
- Microsoft Exchange Server 2019 Cumulative Update 3
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26855
- https://nvd.nist.gov/vuln/detail/CVE-2021-26855
This critical severity vulnerability with a CVSS score of 9.1 was published on 2021-03-09 via Microsoft. 🚨 A public proof-of-concept exploit is available on GitHub. EPSS score: 100.0% (top 0% of all CVEs by exploitation probability). Affected: Microsoft Exchange Server 2016 Cumulative Update 19, Microsoft Exchange Server 2019 Cumulative Update 8, Microsoft Exchange Server 2019 and 5 more.
Risk Timeline
CVE Disclosed2021-03-09 · 1989 days ago
Public PoC Exploit AvailableWeaponised proof-of-concept code is publicly accessible
Remediation Resources
Official Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26855NVD / MITRE
nvd.nist.gov/vuln/detail/CVE-2021-26855Related Vulnerabilities
| CVE | Title | Severity | CVSS |
|---|---|---|---|
| CVE-2026-63508 | Microsoft Planetary Computer Pro Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
| CVE-2026-65667 | Microsoft Teams Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
| CVE-2026-56191 | Microsoft Exchange Online Tampering Vulnerability | CRITICAL | 10.0 |
| CVE-2026-57106 | Data Quality Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
| CVE-2026-23652 | Microsoft Power Pages Remote Code Execution Vulnerability | CRITICAL | 10.0 |
| CVE-2026-41104 | Microsoft Planetary Computer Pro Information Disclosure Vulnerability | CRITICAL | 10.0 |
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