CVE-2026-24052: Claude Code has a Domain Validation Bypass which Allows Automatic Requests to Attacker-Controlled Domains

Published Feb 3, 2026
·
Updated

Claude Code contained insufficient URL validation in its trusted domain verification mechanism for WebFetch requests. The application used a startsWith() function to validate trusted domains (e.g., docs.python.org, modelcontextprotocol.io), this could have enabled attackers to register domains like modelcontextprotocol.io.example.com that would pass validation. This could enable automatic requests to attacker-controlled domains without user consent, potentially leading to data exfiltration.

Users on standard Claude Code auto-update have received this fix already. Users performing manual updates are advised to update to the latest version.

Thank you to hackerone.com/47sid-praetorian for reporting this issue!

Other sources

Claude Code is an agentic coding tool. Prior to version 1.0.111, Claude Code contained insufficient URL validation in its trusted domain verification mechanism for WebFetch requests. The application used a startsWith() function to validate trusted domains (e.g., docs.python.org, modelcontextprotocol.io), this could have enabled attackers to register domains like modelcontextprotocol.io.example.com that would pass validation. This could enable automatic requests to attacker-controlled domains without user consent, potentially leading to data exfiltration. This issue has been patched in version 1.0.111.

— MITRE

Affected Software

2 affected componentsFixes available
npm/@anthropic-ai/claude-code<1.0.111
1.0.111
Anthropic Claude Code Node.js<1.0.111

Event History

Feb 3, 2026
Advisory Published
via GitHub·07:15 PM
Data Sourced
via GitHub·07:15 PM
DescriptionWeaknessAffected Software
CVE Published
via MITRE·08:49 PM
Data Sourced
via MITRE·08:49 PM
DescriptionWeakness
Data Sourced
via NVD·09:16 PM
DescriptionSeverityWeaknessAffected Software
Jun 19, 58090
Event
via FIRST·04:42 PM
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Frequently Asked Questions

1

What is the severity of CVE-2026-24052?

CVE-2026-24052 has been classified as a high severity vulnerability due to its potential to allow automatic requests to attacker-controlled domains.

2

How do I fix CVE-2026-24052?

To fix CVE-2026-24052, update the affected package to version 1.0.111 or later.

3

What is the main issue with CVE-2026-24052?

The main issue with CVE-2026-24052 is insufficient URL validation in the trusted domain verification mechanism for WebFetch requests.

4

Which software versions are affected by CVE-2026-24052?

CVE-2026-24052 affects versions of Claude Code up to and including 1.0.111.

5

What type of attacks can CVE-2026-24052 facilitate?

CVE-2026-24052 can facilitate attacks that redirect communications to attacker-controlled domains due to the validation bypass.

Company

Resources

Contact

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CVE-2026-24052 - Claude Code has a Domain Validation Bypass which Allows Automatic Requests to Attacker-Controlled Domains - SecAlerts