Vulnerability in Microsoft Visual Studio Code Copilot Chat Extension
CVE-2026-21523
Time-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.008 (55.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: -0.000
Affected products
- Microsoft Visual Studio Code Copilot Chat Extension — versions 0.27.0
- Microsoft Visual Studio Code — versions 1.0.0
- Microsoft Visual Studio Code
Weakness classification (CWE)
References
- GitHub Copilot and Visual Studio Code Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21523?
- CVE-2026-21523 is a high-severity vulnerability in Microsoft Visual Studio Code Copilot Chat Extension, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 8.0/10. Published 2026-02-10.
- How severe is CVE-2026-21523?
- High severity. CVSS v3 base score is 8.0 out of 10.