CVE-2026-24052
Claude Code has a Domain Validation Bypass which Allows Automatic Requests to Attacker-Controlled Domains
Description
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!
How to fix CVE-2026-24052
To remediate CVE-2026-24052, upgrade the affected package to a fixed version below.
- —upgrade to 1.0.111 or later
Is CVE-2026-24052 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 1.0.111
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |