CRITICAL 9.0 Microsoft PoC
CVE-2021-34523
Microsoft Exchange Server Elevation of Privilege Vulnerability
Microsoft Security Update 2021-Jul: Microsoft Exchange Server Elevation of Privilege Vulnerability
Affected Products
- Microsoft Exchange Server 2013 Cumulative Update 23
- Microsoft Exchange Server 2019 Cumulative Update 9
- Microsoft Exchange Server 2016 Cumulative Update 20
- Microsoft Exchange Server 2016 Cumulative Update 19
- Microsoft Exchange Server 2019 Cumulative Update 8
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523
- https://nvd.nist.gov/vuln/detail/CVE-2021-34523
This critical severity vulnerability with a CVSS score of 9.0 was published on 2021-07-13 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 2013 Cumulative Update 23, Microsoft Exchange Server 2019 Cumulative Update 9, Microsoft Exchange Server 2016 Cumulative Update 20 and 2 more.
Risk Timeline
CVE Disclosed2021-07-13 · 1905 days ago
Public PoC Exploit AvailableWeaponised proof-of-concept code is publicly accessible
Remediation Resources
Official Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2021-34523NVD / MITRE
nvd.nist.gov/vuln/detail/CVE-2021-34523Related 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-2026-65801 | Microsoft Exchange Online Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
| CVE-2026-69836 | Microsoft Entra ID Remote Code Execution Vulnerability | CRITICAL | 10.0 |
| CVE-2026-69843 | Microsoft Fabric Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
| CVE-2026-83711 | Microsoft Azure Active Directory B2C Elevation of Privilege Vulnerability | CRITICAL | 10.0 |
vulnfeed aggregates 12641 vulnerabilities from NVD, CISA KEV,
Ubuntu, Debian, Red Hat, Kubernetes, Exploit-DB, OSS-Security, GitHub and OpenStack — updated every 4 hours.