CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:S/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
EPSS
Percentile
36.7%
Vulnerability Details:
This vulnerability allows remote attackers escalate privileges on affected installations of Microsoft Exchange Server. Authentication and user interaction is required to exploit this vulnerability in that the target must visit a malicious page.
The specific flaw exists within the HasValidCanary function inside of the Canary15 class. The issue results in an insecure generation of cross site request forgery tokens that can be used to install an office-addins. An attacker can leverage this vulnerability to escalate privileges to an administrative account.
Affected Vendors:
Microsoft
Affected Products:
Exchange Server
Vendor Response:
Microsoft has issued an update to correct this vulnerability. More details can be found at: <https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-24085>
Proof of Concept:
CVSS2
Attack Vector
NETWORK
Attack Complexity
MEDIUM
Authentication
SINGLE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:M/Au:S/C:P/I:P/A:P
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
EPSS
Percentile
36.7%