High

Command Injection RCE in GitHub Copilot and Visual Studio

IdentifiersCVE-2026-21256CWE-77· Improper Neutralization of Special…

CVE-2026-21256 is a remote code execution vulnerability affecting GitHub Copilot and Visual Studio. Microsoft describes the issue as improper neutralization of special elements used in a command, i.e., command injection. The available content indicates that an unauthorized attacker can exploit the flaw over a network, and that user interaction is required. The published CVSS v3.1 vector is AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, indicating low attack complexity, no privileges required, and high impact to confidentiality, integrity, and availability upon successful exploitation. The supporting content also notes Microsoft associated the issue with CWE-77 and CWE-94; based on the description, CWE-77 is the most directly applicable classification.

For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation provides remote code execution in the context of the affected GitHub Copilot and Visual Studio environment. Given the CVSS impacts of C:H/I:H/A:H, exploitation could allow an attacker to run arbitrary commands, compromise the confidentiality and integrity of accessible data, and disrupt availability of the affected system or development environment. The ultimate blast radius depends on the privileges and access available to the vulnerable process and the surrounding developer workstation or build environment.

Mitigation

If you can’t patch tonight, do this now.

No specific vendor workaround or mitigation is provided in the supplied content. Where immediate patching is not possible, reduce exposure by limiting use of untrusted or externally supplied content and prompts in affected developer environments, restricting network egress and command execution paths from developer tools where feasible, and running development tools with least privilege until patches can be applied.

Remediation

Patch, then assume compromise.

Apply Microsoft's February 2026 security updates for supported affected versions of GitHub Copilot and Visual Studio, as referenced in the MSRC Update Guide entry for CVE-2026-21256. Prioritize patching developer workstations and any environments where Visual Studio with GitHub Copilot is installed. Verify successful installation through normal Microsoft update validation processes.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

GitHubCopilotapplication

Microsoft CorporationVisual Studioapplication

Microsoft CorporationVisual Studio 2022application

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

11 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

11 SOURCESView more in app

nsfocus globalNews

Mar 4, 2026

Microsoft’s February Security Update of High-Risk Vulnerability Notice for Multiple Products - NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyber attacks.

A remote code execution vulnerability affecting GitHub Copilot integration in Microsoft Visual Studio.

thecyberexpress com vulnerabilitiesNews

Feb 11, 2026

Microsoft Patch Tuesday February 2026 Fixes 6 Zero-Days

A vulnerability affecting GitHub Copilot and Visual Studio; specific impact type not provided in the content.

cyber security newsNews

Feb 10, 2026

Microsoft Patch Tuesday February 2026 - 54 Vulnerabilities Fixed, Including 6 Zero-days

A remote code execution vulnerability affecting GitHub Copilot and Visual Studio.

bleeping computerNews

Feb 10, 2026

Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws

A remote code execution vulnerability affecting GitHub Copilot and Visual Studio (no additional details provided in the content).

+2 more in the timeline

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity4

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-21256

NVD

nvd.nist.gov/vuln/detail/CVE-2026-21256

MITRE CWE · CWE-77

Improper Neutralization of Special Elements…

Vendor Advisory

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