CVE-2026-58649: .NET Information Disclosure Vulnerability

Overview

Severity

Medium (CVSS 6.5)

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Category

Information Disclosure

Exploit Status

Not Exploited

Exploitation Likelihood

Less Likely

Patch Tuesday

2026-Sep

Released

2026-09-08

EPSS Score

0.27% (percentile: 19.4%)

Description

Origin validation error in .NET allows an unauthorized attacker to disclose information over a network.

FAQ

What type of information could be disclosed by this vulnerability? Successful exploitation could disclose developer-time hot reload data, including application metadata, intermediate language updates, debugging information, method names, string literals, and file paths.

Affected Products (14)

Developer Tools

• Microsoft Visual Studio 2022 version 17.14
• .NET 11.0 installed on Linux
• .NET 11.0 installed on Mac OS
• .NET 8.0 installed on Windows
• .NET 8.0 installed on Mac OS
• .NET 8.0 installed on Linux
• .NET 9.0 installed on Mac OS
• .NET 9.0 installed on Windows
• .NET 9.0 installed on Linux
• Microsoft Visual Studio 2026 version 18.9
• .NET 11.0 installed on Windows
• .NET 10.0 installed on Windows
• .NET 10.0 installed on Linux
• .NET 10.0 installed on Mac OS

Security Updates (6)

• Release Notes
• Security Update
• 5126104
• 5126105
• Release Notes
• 5126106

Acknowledgments

<a href="https://www.linkedin.com/in/weeraphat-srisutham/">Weeraphat Srisutham</a>

Revision History

• 2026-09-08: Information published.