Claude Code has a Domain Validation Bypass which Allows Automatic Requests to Attacker-Controlled Domains
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!
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @anthropic-ai/claude-code | < 1.0.111 | 1.0.111 |
References
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-601- Platform
- npm
- Package
@anthropic-ai/claude-code- Disclosed
- 03.02.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vhw5-3g5m-8ggf - CC BY 4.0
Vulnerability history: @anthropic-ai/claude-code
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 29
- First → latest
- 06.2025 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 23
- Medium 4
- Low 2
Disclosures per year
- 2025: 13
- 2026: 16
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Claude Code has a Domain Validation Bypass which Allows Automatic Requests to Attacker-Controlled Domains this entry
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