What is the CVSS score of CVE-2026-21256?

CVE-2026-21256 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

How to fix or mitigate CVE-2026-21256?

Within 24 hours: Inventory all GitHub Copilot and Visual Studio installations across the organization and disable Copilot features until further notice. Within 7 days: Conduct incident response readiness drills and implement enhanced code review processes for any commits generated during the vulnerable period. Within 30 days: Establish a vendor communication protocol with GitHub and Microsoft for patch timelines, perform forensic analysis of development environments for potential compromise, and develop a phased re-enablement strategy pending patch availability.

Github CVE-2026-21256

HIGH

Command Injection (CWE-77)

2026-02-10 secure@microsoft.com

Command Injection Github Microsoft AI / ML Visual Studio 2022

8.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

Access

Craft malicious input with special characters
Exploit

User opens file in GitHub Copilot or Visual Studio
Execution

Command injection in code processing
Impact

Execute arbitrary code with user privileges

Vulnerability Assessment

Weakness	CWE CWE-77 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Command injection prevention MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Exploitation Conditions	GitHub Copilot extension or Visual Studio with Copilot enabled installed and active. User interaction required to open attacker-controlled file containing specially crafted input that triggers command injection in code suggestion/completion workflow.
Impact	CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: None. User interaction: Required. Exploitation no authentication required. Exploitable via remote/network.
Exploit ScenarioDerived	A remote attacker without authentication could exploit this vulnerability to compromise the affected system.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Remote code execution in GitHub Copilot and Visual Studio 2022 via command injection allows unauthenticated attackers to execute arbitrary code over the network with user interaction. The vulnerability stems from improper sanitization of special elements in commands, enabling attackers to break out of intended command contexts and inject malicious payloads. No patch is currently available for this high-severity issue affecting both development environments.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 22:02 CVSS 8.8

Improper neutralization of special elements used in a command ('command injection') in GitHub Copilot and Visual Studio allows an unauthorized attacker to execute code over a network. [CVSS 8.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affected Packages

microsoft visual_studio_2022_version_17_14_17_14_26 fix: Microsoft Visual Studio 2022 version 17.14 17.14.26

microsoft visual_studio_2026_version_18_3_18_3_0 fix: Microsoft Visual Studio 2026 version 18.3 18.3.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in microsoft

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Classified as CWE-77 (Command Injection). Affects Visual Studio 2022. Improper neutralization of special elements used in a command ('command injection') in GitHub Copilot and Visual Studio allows an unauthorized attacker to execute code over a network.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionCVE.org

Improper neutralization of special elements used in a command ('command injection') in GitHub Copilot and Visual Studio allows an unauthorized attacker to execute code over a network.

Executive ViewAI

Why It Matters

CVE-2026-21256 is a critical command injection vulnerability affecting GitHub Copilot and Visual Studio that allows remote code execution without authentication. Any developer using these tools is a potential attack vector that could compromise source code, credentials, and internal systems. Immediate action is required to mitigate exposure while waiting for vendor patches.

Business Impact: High

Compensating Controls

Disable GitHub Copilot and AI code completion features in Visual Studio across all development environments. Implement network segmentation to restrict outbound connections from developer workstations to GitHub and Microsoft cloud services. Enforce mandatory code review and approval processes with heightened scrutiny for all commits. Monitor for suspicious network connections and process execution from development tools. Consider temporarily restricting development activities to air-gapped environments if feasible. Enable comprehensive logging and monitoring of IDE activities and Git operations.

Threat Intelligence Overview

EPSS Score

0.0%

Top 91% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact

High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

OS Command Injection CRITICAL

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

Affected Products (CPE)CVE.org

cpe:2.3:a:microsoft:visual_studio_2022:*:*:*:*:*:-:*:*

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References

Advisories & patches

ADVISORY https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21256

Search Externally

GitHub PoC

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