OpenClaw has SSRF guard bypass via IPv6 transition over ISATAP

Summary

## Summary OpenClaw's SSRF hostname/IP guard did not detect ISATAP embedded IPv4 addresses (`...:5efe:w.x.y.z`). A crafted URL containing an ISATAP IPv6 literal could embed a private IPv4 target (for example loopback) and bypass private-address filtering in URL-fetching paths.

## Severity Assessment Rated **medium**: the bug weakens SSRF protections in URL fetch flows, but impact depends on reaching a URL-fetching path with attacker-controlled input and is generally constrained to internal network access attempts.

## Affected Packages / Versions - Package: `openclaw` (npm) - Affected: `>=2026.1.20 <=2026.2.17` - Latest published at patch time: `2026.2.17` - Patched release: `2026.2.19`

## Security Policy Context Per `SECURITY.md`, OpenClaw's web/gateway surface is intended for local use by default, public internet exposure is out-of-scope, and prompt-injection reports are out-of-scope for bounty handling. This advisory tracks a core SSRF-guard bypass in fetch protections.

## Impact This can permit SSRF-style access attempts to internal/private network targets through URL ingestion/fetch paths that rely on shared hostname/IP blocking.

## Fix - Added RFC 5214 ISATAP embedded-IPv4 detection to the shared SSRF classifier. - Centralized hostname/IP blocking through `isBlockedHostnameOrIp` and routed relevant validators to that shared path. - Added regression tests for ISATAP private vs public embedded IPv4 handling.

## Fix Commit(s) - `d51929ecb52fe65e90bf36795f4247feb29eb8aa`

OpenClaw thanks @zpbrent for reporting.