Vulnerability Details : CVE-2021-26855
Public exploit exists!
Used for ransomware!
Microsoft Exchange Server Remote Code Execution Vulnerability
Vulnerability category: Server-side request forgery (SSRF) Execute code
CVE-2021-26855 is in the CISA Known Exploited Vulnerabilities Catalog
This issue is known to have been leveraged as part of a ransomware campaign.
CISA vulnerability name:
Microsoft Exchange Server Remote Code Execution Vulnerability
CISA required action:
Apply updates per vendor instructions.
CISA description:
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
Notes:
Reference CISA's ED 21-02 (https://www.cisa.gov/emergency-directive-21-02) for further guidance and requirements.
Added on
2021-11-03
Action due date
2021-04-16
Exploit prediction scoring system (EPSS) score for CVE-2021-26855
Probability of exploitation activity in the next 30 days: 97.51%
Percentile, the proportion of vulnerabilities that are scored at or less: ~ 100 % EPSS Score History EPSS FAQ
Metasploit modules for CVE-2021-26855
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Microsoft Exchange ProxyLogon RCE
Disclosure Date: 2021-03-02First seen: 2021-03-23exploit/windows/http/exchange_proxylogon_rceThis module exploit a vulnerability on Microsoft Exchange Server that allows an attacker bypassing the authentication, impersonating as the admin (CVE-2021-26855) and write arbitrary file (CVE-2021-27065) to get the RCE (Remote Code Execution). By -
Microsoft Exchange ProxyLogon Scanner
Disclosure Date: 2021-03-02First seen: 2021-03-23auxiliary/scanner/http/exchange_proxylogonThis module scan for a vulnerability on Microsoft Exchange Server that allows an attacker bypassing the authentication and impersonating as the admin (CVE-2021-26855). By chaining this bug with another post-auth arbitrary-file-write vulnerability t -
Microsoft Exchange ProxyLogon Collector
Disclosure Date: 2021-03-02First seen: 2021-03-23auxiliary/gather/exchange_proxylogon_collectorThis module exploit a vulnerability on Microsoft Exchange Server that allows an attacker bypassing the authentication and impersonating as the admin (CVE-2021-26855). By taking advantage of this vulnerability, it is possible to dump all mailboxes (
CVSS scores for CVE-2021-26855
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source |
---|---|---|---|---|---|
7.5
|
HIGH | AV:N/AC:L/Au:N/C:P/I:P/A:P |
10.0
|
6.4
|
NIST |
9.8
|
CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
3.9
|
5.9
|
NIST |
9.1
|
CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N |
3.9
|
5.2
|
Microsoft Corporation |
CWE ids for CVE-2021-26855
-
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-26855
-
http://packetstormsecurity.com/files/161846/Microsoft-Exchange-2019-SSRF-Arbitrary-File-Write.html
Microsoft Exchange 2019 SSRF / Arbitrary File Write ≈ Packet StormExploit;Third Party Advisory;VDB Entry
-
http://packetstormsecurity.com/files/162610/Microsoft-Exchange-2019-Unauthenticated-Email-Download.html
Microsoft Exchange 2019 Unauthenticated Email Download ≈ Packet StormExploit;Third Party Advisory;VDB Entry
-
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855
CVE-2021-26855 - Security Update Guide - Microsoft - Microsoft Exchange Server Remote Code Execution VulnerabilityPatch;Vendor Advisory
-
http://packetstormsecurity.com/files/162736/Microsoft-Exchange-ProxyLogon-Collector.html
Microsoft Exchange ProxyLogon Collector ≈ Packet StormExploit;Third Party Advisory;VDB Entry
-
http://packetstormsecurity.com/files/161938/Microsoft-Exchange-ProxyLogon-Remote-Code-Execution.html
Microsoft Exchange ProxyLogon Remote Code Execution ≈ Packet StormExploit;Third Party Advisory;VDB Entry
Products affected by CVE-2021-26855
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_8:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_9:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_21:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:-:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_22:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_5:*:*:*:*:*:*
- cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_6:*:*:*:*:*:*