(Pwn2Own) Microsoft Exchange External Control of File Path Remote Code Execution Vulnerability

August 11th, 2026
ZDI-26-535 ZDI-CAN-31481

CVE ID

CVE-2026-62911

CVSS Score

7.2 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected Vendors

Microsoft

Affected Products

Exchange

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Exchange. Although authentication is required to exploit this vulnerability, the existing authentication mechanism can be bypassed.

The specific flaw exists within the handling of file paths. The issue results from the lack of proper validation of a user-supplied path prior to using it in file operations. A remote attacker can exploit this vulnerability to execute arbitrary code in the context of 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-2026-62911

Disclosure Timeline

  • 2026-05-21 - Vulnerability reported to vendor
  • 2026-08-11 - Coordinated public release of advisory
  • 2026-08-11 - Advisory Updated

Credit

Orange Tsai (@orange_8361) from DEVCORE Research Team

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