---
cve: "CVE-2021-26855"
severity: "CRITICAL"
cvss: 9.1
epss: "100%"
vendor: "Microsoft"
kev: true
exploited: true
published: "2021-03-03 00:15:12"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-10T01:30:31+02:00"
---

# CVE-2021-26855

> 9.1 CRITICAL · ⚠️ CISA KEV (1772 Tage) · 🔓 Exploited

## Beschreibung

Microsoft Exchange Server Remote Code Execution Vulnerability

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Exploit-Evidenz

- [EDB-49895 — Microsoft Exchange 2019 - Unauthenticated Email Download (Metasploit)](https://www.exploit-db.com/exploits/49895)
- [EDB-49879 — Microsoft Exchange 2019 - Unauthenticated Email Download](https://www.exploit-db.com/exploits/49879)
- [EDB-49663 — Microsoft Exchange 2019 - Server-Side Request Forgery](https://www.exploit-db.com/exploits/49663)
- [EDB-49637 — Microsoft Exchange 2019 - Server-Side Request Forgery (Proxylogon) (PoC)](https://www.exploit-db.com/exploits/49637)

## Referenzen

- <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26855>
- <http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html>
- <http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html>
- <http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html>
- <http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html>
- <https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855>
- <https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-26855>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2021-26855) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_