CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability
Actively exploited
- In the CISA exploited-vulnerabilities catalogue since Nov 3, 2021
- US federal agencies must remediate it by May 3, 2022 (BOD 22-01)
- Attacked 1 day before the vulnerability was made public
- Confirmed by sensors, not only by reports
- Used in ransomware campaigns
Apply updates per vendor instructions.
Source: CISA KEV · Sep 1, 2026 Sep 1, 2026 Aug 31, 2026 Aug 30, 2026 Aug 29, 2026 Aug 28, 2026
CVSS score9.1 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NWeakness type (CWE)CWE-918, CWE-918
Vendorsmicrosoft
Affected products
| Vendors | Prodotto | Versioni |
|---|---|---|
| microsoft | exchange server | 2013 |
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