ZDI-CAN-31262: ZDI-26-534: (Pwn2Own) Microsoft Exchange Capture-Replay Authentication Bypass Vulnerability
Published Aug 11, 2026
·Updated
This vulnerability allows remote attackers to bypass authentication on affected installations of Microsoft Exchange. Authentication is not required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.1. The following CVEs are assigned: CVE-2026-62911.
Affected Software
1 affected component
Microsoft Microsoft Exchange
Event History
Aug 11, 2026
Advisory Published
via ZDI·05:00 AM
Data Sourced
via ZDI·05:00 AM
Description
Frequently Asked Questions
1
What is ZDI-CAN-31262?
ZDI-CAN-31262 is a security vulnerability regarding an authentication bypass in Microsoft Exchange.
2
What is the severity of ZDI-CAN-31262?
The severity of ZDI-CAN-31262 is rated at 8.1 on the CVSS scale.
3
How do I fix ZDI-CAN-31262?
To fix ZDI-CAN-31262, users should apply the latest security patches released by Microsoft for Exchange.
4
Who is affected by ZDI-CAN-31262?
Organizations using affected installations of Microsoft Exchange are vulnerable to ZDI-CAN-31262.
5
What type of attack is associated with ZDI-CAN-31262?
ZDI-CAN-31262 allows remote attackers to exploit an authentication bypass without requiring authentication.