Advisory Details

June 16th, 2023

(Pwn2Own) Microsoft SharePoint ValidateTokenIssuer Improper Verification of Cryptographic Signature Authentication Bypass Vulnerability

CVE ID	CVE-2023-29357
CVSS SCORE	9.8, AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS	Microsoft
AFFECTED PRODUCTS	SharePoint
VULNERABILITY DETAILS	This vulnerability allows remote attackers to bypass authentication on affected installations of Microsoft SharePoint. Authentication is not required to exploit this vulnerability. The specific flaw exists within the ValidateTokenIssuer method. The issue results from the lack of proper verification of a cryptographic signature. An attacker can leverage this vulnerability to bypass authentication on the system.
ADDITIONAL DETAILS	Microsoft has issued an update to correct this vulnerability. More details can be found at: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-29357
DISCLOSURE TIMELINE	2023-03-30 - Vulnerability reported to vendor 2023-06-16 - Coordinated public release of advisory
CREDIT	Nguyễn Tiến Giang (@testanull) of STAR Labs SG Pte. Ltd.

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