Visual Studio Copilot and SSMS remote code execution vulnerability (CVE-2026-103572)
Visual Studio Copilot and SSMS Remote Code Execution (CVE-2026-103572)
Security researcher Johann Rehberger disclosed a path validation bypass vulnerability in Visual Studio Copilot, CVE-2026-103572. Microsoft rated it Important-level remote code execution and released a fix in the October 13 Patch Tuesday. The root cause is that Windows ignores trailing dots in file names, so an Agent can bypass checks on protected configuration files by writing names such as settings.json. The flaw is in Microsoft.VisualStudio.Copilot.Core.dll, shared by Visual Studio and SSMS, and older versions such as Visual Studio 2022 are also affected. The vulnerability was reported to MSRC on August 4, confirmed by Microsoft on September 16, has a CVSS of 8.8 but a bounty of $0. The fix adds a GetFullPath call to strip trailing dots and normalize paths.
The author uses the example of bypassing path validation by appending a trailing dot to a file name to illustrate that an Agent's security controls need to hold even when the Agent itself is hijacked or compromised.