CVE-2026-21523Network attack vector

Authenticated code execution via Copilot validation bypass

Published Feb 10, 2026 · Updated Feb 10, 2026

Remote code execution in Microsoft Visual Studio Code before 1.110.1 allows remote authenticated users to execute code through Copilot Chat. Copilot Chat displays agent-supplied look-alike URLs without punycode encoding and fails to fully validate apply_patch input against the sensitive-file approval boundary. Exploitation requires an affected prompt-injected agent session, a GPT-family model for the patch path, and user approval to open or fetch a deceptive URL.

CVSS severity8.0
High
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Microsoft Visual Studio Code before 1.110.1 allows remote authenticated users to execute code through Copilot Chat. Copilot Chat displays agent-supplied look-alike URLs without punycode encoding and fails to fully validate apply_patch input against the sensitive-file approval boundary. Exploitation requires an affected prompt-injected agent session, a GPT-family model for the patch path, and user approval to open or fetch a deceptive URL.

The record

CVE
CVE-2026-21523
Published
Feb 10, 2026
Updated
Feb 10, 2026
Vendor
Microsoft
Product
Visual Studio Code
Classifications
CWE-367, CAPEC-29, T1204.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <1.109.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Visual Studio Codeversion=1.0.0 <1.109.2

Published CVSS scores

8.0Microsoft CorporationCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CAPEC-29Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions
T1204.001User Execution: Malicious Link

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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