CVE-2026-21516
Published: 10 February 2026
Summary
CVE-2026-21516 is a high-severity Command Injection (CWE-77) vulnerability in Microsoft Github Copilot. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked at the 8.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
This vulnerability is AI-related — categorised as Enterprise AI Assistants.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
SI-10 requires validation of information inputs to neutralize special elements, directly preventing command injection vulnerabilities like CVE-2026-21516.
SI-2 mandates timely flaw remediation, addressing the specific improper neutralization defect in GitHub Copilot.
AC-6 enforces least privilege to limit the impact of arbitrary code execution resulting from successful command injection.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Command injection (CWE-77) directly enables arbitrary command execution on the client (T1059); network-based exploitation of the vulnerable Copilot component for client-side code execution (T1203).
NVD Description
Improper neutralization of special elements used in a command ('command injection') in Github Copilot allows an unauthorized attacker to execute code over a network.
Deeper analysisAI
CVE-2026-21516 is a command injection vulnerability (CWE-77) in GitHub Copilot, caused by improper neutralization of special elements used in a command. This flaw allows an unauthorized attacker to execute code over a network and affects the GitHub Copilot software component. Published on 2026-02-10, it carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating high severity due to its network reach, low complexity, and lack of required privileges.
An unauthorized attacker (PR:N) can exploit this vulnerability remotely over the network (AV:N) with low attack complexity (AC:L), though it requires user interaction (UI:R). Successful exploitation enables arbitrary code execution with high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), potentially compromising the victim's system.
The Microsoft Security Response Center advisory provides further details on this vulnerability at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21516.
Details
- CWE(s)
Affected Products
AI Security AnalysisAI
- AI Category
- Enterprise AI Assistants
- Risk Domain
- N/A
- OWASP Top 10 for LLMs 2025
- None mapped
- Classification Reason
- Matched keywords: copilot