HighVulnerability

CVE-2026-21523: GitHub Copilot and Visual Studio race condition allowing network code execution

Source: NVD(opens in a new tab)
Identifier: CVE-2026-21523
Published: February 10, 2026
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.8%

Summary

CVE-2026-21523 is a time-of-check time-of-use (TOCTOU) race condition, classified as CWE-367, in GitHub Copilot and Visual Studio. The source states that an authorized attacker can exploit it to execute code over a network. NIST has not yet provided an NVD assessment, and the entry was published 02/10/2026.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Details

Scores and exploitation

CVSS score: 8(high)
EPSS: 0.8%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 4, 2026.

Weaknesses and techniques

Weakness (CWE): CWE-367
Attack pattern (CAPEC): CAPEC-27

Affected

Vendors: Microsoft

Classification

Attack type: Other
Attack sophistication: Moderate
AI component targeted: Plugin
Impact: Integrity,
Confidentiality
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2026-21523

First tracked: February 15, 2026 at 08:51 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 85% (self-assessed)

Topics

Coding assistants

Summary

Mitigation

Topics

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