CVE-2026-24052: Anthropic Claude Code domain validation bypass in WebFetch

CVE-2026-24052 · Severity: medium · CVSS 4 · Published 2026-02-03

Claude Code is an AI-powered development assistant that performs web requests to fetch documentation and resources. A flaw in how the application validates trusted domains allows attackers to register lookalike domains (e.g., modelcontextprotocol.io.attacker.com) that pass the validation checks. This could trick Claude Code into automatically fetching content from attacker-controlled servers, potentially exposing sensitive data without user awareness.

Technologies: Anthropic Claude Code, @anthropic-ai/claude-code (npm). Vendors: Anthropic, npm.

Quick answers

Is CVE-2026-24052 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-24052 being exploited in the wild.
How severe is CVE-2026-24052?
Medium severity, with a CVSS score of 4, published 3 February 2026.
Which products and versions are affected?
Anthropic Claude Code < 1.0.111; @anthropic-ai/claude-code (npm) SEMVER:introduced=0,fixed=1.0.111.
Is there a fix for CVE-2026-24052?
Yes. @anthropic-ai/claude-code (npm): upgrade to 1.0.111 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-24052 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-24052?
Check whether you run Anthropic Claude Code or @anthropic-ai/claude-code (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • @anthropic-ai/claude-code (npm): upgrade to 1.0.111 or later
    npm install @anthropic-ai/claude-code@1.0.111

Technical details

Claude Code's WebFetch mechanism uses a flawed URL validation check—a simple startsWith() function—to verify that requests go only to trusted domains like docs.python.org and modelcontextprotocol.io. An attacker can bypass this by registering a domain that starts with a trusted domain name (e.g., modelcontextprotocol.io.attacker.com), which would pass the validation. No authentication is required; the vulnerability is triggered when Claude Code automatically makes a request to the attacker-controlled domain, potentially resulting in data exfiltration. The attack vector is network-based and requires only passive user interaction (e.g., viewing a prompt or file that triggers the WebFetch). Patches are available as of version 1.0.111, and users on auto-update have already received the fix.

Affected products

  • Anthropic Claude Code < 1.0.111

Identifiers

  • CVE-2026-24052
  • GHSA-vhw5-3g5m-8ggf

Timeline

  • 2026-02-03: disclosed
  • 2026-02-03: patched: Fix released in version 1.0.111

References

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