open-websearch has SSRF in `fetchWebContent` MCP tool: bracketed IPv6 literals and non-resolving hostname check bypass `isPrivateOrLocalHostname` — CVE-2026-42260

Summary

### Summary `src/utils/urlSafety.ts` exposes `isPublicHttpUrl` / `assertPublicHttpUrl`, used to gate the MCP `fetchWebContent` tool against private-network targets. The check has two defects that together allow **non-blind SSRF with the response body returned to the caller**: 1. **Bracketed IPv6 literals are never recognized.** Node's WHATWG `URL.hostname` keeps the surrounding `[…]` for IPv6 literals.…

Product

npm: open-websearch

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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