This vulnerability (CWE-77) in Microsoft Visual Studio Code CoPilot Chat Extension 0.27.0 involves improper neutralization of special elements in commands, enabling command injection. An attacker can exploit this flaw remotely without privileges and with user interaction to bypass security controls. The CVSS 3.1 score is 8.8 (high), reflecting network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability. Microsoft has published an official fix for this vulnerability.

Successful exploitation allows an attacker to bypass security features remotely, potentially leading to full compromise of the affected system's confidentiality, integrity, and availability. This could result in unauthorized command execution within the context of the vulnerable extension.

An official fix is available from Microsoft. Users should apply the vendor-provided patch promptly to remediate this vulnerability. Refer to the Microsoft security update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21518 for detailed patch information and instructions.