SB2021101214 - Multiple vulnerabilities in Microsoft Exchange Server

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Main Vulnerability Database SB2021101214

SB2021101214 - Multiple vulnerabilities in Microsoft Exchange Server

Published: October 12, 2021

Security Bulletin ID SB2021101214
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 4
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 4 vulnerabilities.


1) Security restrictions bypass (CVE-ID: CVE-2021-26427)

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

CVSSv4: CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Green


The vulnerability allows a remote user to escalate privileges on the system.

The vulnerability exists due to application does not properly impose security restrictions. A remote user on the local network can send specially crafted data to the Exchange server and execute arbitrary code with elevated privileges.


2) Input validation error (CVE-ID: CVE-2021-34453)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send  specially crafted input to the server and perform a denial of service (DoS) attack.


3) Security restrictions bypass (CVE-ID: CVE-2021-41348)

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

CVSSv4: CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green


The vulnerability allows a remote user to escalate privileges on the system.

The vulnerability exists due to application does not properly impose security restrictions, which leads to security restrictions bypass and privilege escalation.


4) Cross-site scripting (CVE-ID: CVE-2021-41350)

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green


The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability exists due to insufficient sanitization of user-supplied data. A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in user's browser in context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform spoofing attacks.


Remediation

Install update from vendor's website.

References