Microsoft Windows IKEv2 AES-GCM Decryption Integer Underflow Remote Code Execution Vulnerability

September 8th, 2026
ZDI-26-622 ZDI-CAN-31212

CVE ID

CVE-2026-50696

CVSS Score

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

Affected Vendors

Microsoft

Affected Products

Windows

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Windows. Authentication is not required to exploit this vulnerability, but only systems with specific IPsec configurations are vulnerable.

The specific flaw exists within the IKEEXT service. The issue results from the lack of proper validation of user-supplied data, which can result in an integer underflow before writing to memory. An attacker may be able to leverage this vulnerability to execute 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-2026-50696

Disclosure Timeline

  • 2026-05-11 - Vulnerability reported to vendor
  • 2026-09-08 - Coordinated public release of advisory
  • 2026-09-08 - Advisory Updated

Credit

Richard Chen of TrendAI Research

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