diff --git a/pkgs/lab-ops-hub/container/app.py b/pkgs/lab-ops-hub/container/app.py
index 8702c414e..3f39b6e7c 100644
--- a/pkgs/lab-ops-hub/container/app.py
+++ b/pkgs/lab-ops-hub/container/app.py
@@ -56,6 +56,12 @@ def validate_crawl_url(raw):
     # the zone id). Refuse every % host, fail-closed (#505).
     if "%" in host:
         raise ValueError(f"refusing to crawl percent-encoded host {host}")
+    # A space or control character in the host is not a DNS name: WHATWG
+    # rejects it outright, urlparse hands it through verbatim, and
+    # http.client only raises for it deep inside the fetcher — the same
+    # lazy-failure shape #502 fixed for ports. Refuse up front (#507).
+    if any(ord(c) <= 0x20 for c in host):
+        raise ValueError(f"refusing to crawl host with whitespace {host!r}")
     if host == "localhost" or host.endswith(_BLOCKED_SUFFIXES):
         raise ValueError(f"refusing to crawl local host {host}")
     try:
@@ -76,6 +82,17 @@ def validate_crawl_url(raw):
                     f"refusing to crawl host {host}: numeric final label "
                     "but not a valid IPv4 address"
                 )
+            # A bracketed host occupied the IP-literal position
+            # ([v1.fe80::], [v7.a] and other IPvFuture forms) but is not
+            # a valid IPv6 literal — urlparse strips the brackets, so
+            # look at the netloc. Fail closed instead of reclassifying
+            # it as a public DNS name, matching the Worker's validator
+            # (#507).
+            if u.netloc.rsplit("@", 1)[-1].startswith("["):
+                raise ValueError(
+                    f"refusing to crawl host {host}: bracketed literal "
+                    "but not a valid IPv6 address"
+                )
             return raw  # a public DNS name; literal-IP policy does not apply
     embedded = _embedded_ipv4(ip)
     if embedded is not None:
diff --git a/pkgs/lab-ops-hub/test/test_container_validate.py b/pkgs/lab-ops-hub/test/test_container_validate.py
index f8dbf116d..484191ef2 100644
--- a/pkgs/lab-ops-hub/test/test_container_validate.py
+++ b/pkgs/lab-ops-hub/test/test_container_validate.py
@@ -192,6 +192,22 @@ def test_refuses_percent_encoded_hosts_and_zone_ids(self):
         ):
             self.assertRefused(url)
 
+    def test_refuses_space_hosts_and_ipvfuture_literals(self):
+        # A space in the host is not a DNS name: WHATWG rejects it and
+        # http.client only raises for it deep inside the fetcher, so the
+        # validator refuses up front. A bracketed host that is not a
+        # valid IPv6 literal (IPvFuture forms) occupied the IP-literal
+        # position; a DNS name never contains a colon, so it must not be
+        # reclassified as a public DNS name either (#507).
+        for url in (
+            "http://exam ple.com/",
+            "http://exa mple.com/",
+            "http://[v1.fe80::]/",
+            "http://[v7.a]/",
+            "http://[vf.FF]/",
+        ):
+            self.assertRefused(url)
+
     def test_accepts_public_targets(self):
         for url in (
             "https://example.com/page",