CVE-2021-26855 KEV EXPLOIT
9.1
CRITICAL · CVSS 3.1 · EPSS 100% (pctl 100)
Patch first
On CISA KEV — known exploited in the wild, due 2022-05-03.
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Scoring
| CVSS | 9.1 (CRITICAL, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
| EPSS | 100% — more likely to be exploited than 100% of all CVEs |
| Weakness | CWE-918 |
| On CISA KEV | yes — remediate by 2022-05-03 |
| Public exploit | yes |
| Published | 2021-03-03 |
| Last modified | 2026-08-19 |
CISA KEV
| Name | Microsoft Exchange Server Remote Code Execution Vulnerability |
|---|---|
| Added | 2021-11-03 |
| Due | 2022-05-03 |
| Vendor / product | Microsoft / Exchange Server |
| Ransomware use | known |
Affected (1)
| Vendor | Product |
|---|---|
| microsoft | exchange server |
Public exploits
| Source | Title | Date |
|---|---|---|
| exploit-db | Microsoft Exchange 2019 - Unauthenticated Email Download (Metasploit) | 2021-05-21 |
| exploit-db | Microsoft Exchange 2019 - Unauthenticated Email Download | 2021-05-18 |
| exploit-db | Microsoft Exchange 2019 - Server-Side Request Forgery | 2021-03-14 |
| exploit-db | Microsoft Exchange 2019 - Server-Side Request Forgery (Proxylogon) (PoC) | 2021-03-11 |
References
- 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
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