Multiple vulnerabilities in Microsoft Exchange Server

Published: 2021-03-03 | Updated: 2023-05-14

Risk	Critical
Patch available	YES
Number of vulnerabilities	7
CVE-ID	CVE-2021-26412 CVE-2021-26854 CVE-2021-26855 CVE-2021-26857 CVE-2021-26858 CVE-2021-27065 CVE-2021-27078
CWE-ID	CWE-20 CWE-918
Exploitation vector	Network
Public exploit	Vulnerability #3 is being exploited in the wild. Vulnerability #4 is being exploited in the wild. Vulnerability #5 is being exploited in the wild. Vulnerability #6 is being exploited in the wild.
Vulnerable software	Microsoft Exchange Server Server applications / Mail servers
Vendor	Microsoft

Security Bulletin

This security bulletin contains information about 7 vulnerabilities.

1) Input validation error

EUVDB-ID: #VU51174

Risk: High

CVSSv3.1: 7.9 [CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-26412

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26412

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Input validation error

EUVDB-ID: #VU51173

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-26854

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26854

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

3) Server-Side Request Forgery (SSRF)

EUVDB-ID: #VU51171

Risk: Critical

CVSSv3.1: 9.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-26855

CWE-ID: CWE-918 - Server-Side Request Forgery (SSRF)

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted HTTP request to the Microsoft Exchange OWA interface, upload arbitrary file on the server and execute it.

Note, this vulnerability is being actively exploited in the wild.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26855
http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
http://github.com/microsoft/CSS-Exchange/tree/main/Security

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.

4) Input validation error

EUVDB-ID: #VU51170

Risk: Critical

CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-26857

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Note, this vulnerability is being actively exploited in the wild.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26857
http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.

5) Input validation error

EUVDB-ID: #VU51169

Risk: Critical

CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-26858

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Note, this vulnerability is being actively exploited in the wild.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26858
http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.

6) Input validation error

EUVDB-ID: #VU51168

Risk: Critical

CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-27065

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Note, this vulnerability is being actively exploited in the wild.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27065
http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.

7) Input validation error

EUVDB-ID: #VU51172

Risk: High

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-27078

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the system.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 1 15.00.0712.024 - 2019 RTM 15.02.0221.012

CPE2.3

External links

http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27078

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.