diff --git a/sentry_sdk/utils.py b/sentry_sdk/utils.py
index c8dba71106..4948c3bffb 100644
--- a/sentry_sdk/utils.py
+++ b/sentry_sdk/utils.py
@@ -1823,14 +1823,31 @@ def match_regex_list(
 
 def is_sentry_url(client: "sentry_sdk.client.BaseClient", url: str) -> bool:
     """
-    Determines whether the given URL matches the Sentry DSN.
+    Determines whether the given URL's hostname matches the Sentry DSN.
+
+    ``url`` may be an absolute URL or a raw host with an optional port.
     """
-    return (
-        client is not None
-        and client.transport is not None
-        and client.transport.parsed_dsn is not None
-        and client.transport.parsed_dsn.netloc in url
-    )
+    if (
+        client is None
+        or client.transport is None
+        or client.transport.parsed_dsn is None
+    ):
+        return False
+
+    dsn_host = client.transport.parsed_dsn.host
+
+    # ``HTTPConnection.host`` is a raw hostname without brackets for IPv6.
+    if url.lower() == dsn_host.lower():
+        return True
+
+    candidate = url if "://" in url or url.startswith("//") else "//" + url
+
+    try:
+        hostname = urlsplit(candidate).hostname
+    except ValueError:
+        return False
+
+    return hostname is not None and hostname.lower() == dsn_host.lower()
 
 
 def _generate_installed_modules() -> "Iterator[Tuple[str, str]]":
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 1b6d2892b9..6d85c0342f 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -882,15 +882,15 @@ class TestIntegration(Integration):
 
 
 @pytest.fixture
-def mock_client_with_dsn_netloc():
+def mock_client_with_dsn():
     """
-    Returns a mocked Client with a DSN netloc of "abcd1234.ingest.sentry.io".
+    Returns a mocked Client with a DSN host of "abcd1234.ingest.sentry.io".
     """
     mock_client = mock.Mock(spec=sentry_sdk.Client)
     mock_client.transport = mock.Mock(spec=sentry_sdk.Transport)
     mock_client.transport.parsed_dsn = mock.Mock(spec=Dsn)
 
-    mock_client.transport.parsed_dsn.netloc = "abcd1234.ingest.sentry.io"
+    mock_client.transport.parsed_dsn.host = "abcd1234.ingest.sentry.io"
 
     return mock_client
 
@@ -899,13 +899,37 @@ def mock_client_with_dsn_netloc():
     ["test_url", "is_sentry_url_expected"],
     [
         ["https://asdf@abcd1234.ingest.sentry.io/123456789", True],
+        ["HTTP://ABCD1234.INGEST.SENTRY.IO:8443/envelope", True],
+        ["abcd1234.ingest.sentry.io", True],
+        ["abcd1234.ingest.sentry.io:9000", True],
         ["https://asdf@abcd1234.ingest.notsentry.io/123456789", False],
+        ["https://abcd1234.ingest.sentry.io.evil.test/api/1", False],
+        ["https://abcd1234.ingest.sentry.io@attacker.test/api/1", False],
+        ["https://attacker.test/abcd1234.ingest.sentry.io", False],
+        ["https://attacker.test/?next=abcd1234.ingest.sentry.io", False],
+        ["abcd1234.ingest.sentry.io.evil.test", False],
+        ["https://[::1", False],
     ],
 )
-def test_is_sentry_url_true(
-    test_url, is_sentry_url_expected, mock_client_with_dsn_netloc
-):
-    ret_val = is_sentry_url(mock_client_with_dsn_netloc, test_url)
+def test_is_sentry_url(test_url, is_sentry_url_expected, mock_client_with_dsn):
+    ret_val = is_sentry_url(mock_client_with_dsn, test_url)
+
+    assert ret_val == is_sentry_url_expected
+
+
+@pytest.mark.parametrize(
+    ["test_url", "is_sentry_url_expected"],
+    [
+        ["2001:db8::1", True],
+        ["[2001:db8::1]:9000", True],
+        ["HTTP://[2001:DB8::1]:9000/envelope", True],
+        ["http://[2001:db8::2]:9000/envelope", False],
+    ],
+)
+def test_is_sentry_url_ipv6(test_url, is_sentry_url_expected, mock_client_with_dsn):
+    mock_client_with_dsn.transport.parsed_dsn.host = "2001:db8::1"
+
+    ret_val = is_sentry_url(mock_client_with_dsn, test_url)
 
     assert ret_val == is_sentry_url_expected
 
diff --git a/tests/tracing/test_misc.py b/tests/tracing/test_misc.py
index 9690f2ffc0..3afb5dfd1f 100644
--- a/tests/tracing/test_misc.py
+++ b/tests/tracing/test_misc.py
@@ -393,6 +393,26 @@ def test_should_propagate_trace(
             "http://squirrelchasers.ingest.sentry.io/12312012",
             False,
         ),
+        (
+            "https://dogsarebadatkeepingsecrets@squirrelchasers.ingest.sentry.io/12312012",
+            "https://SQUIRRELCHASERS.INGEST.SENTRY.IO/12312012",
+            False,
+        ),
+        (
+            "https://dogsarebadatkeepingsecrets@squirrelchasers.ingest.sentry.io/12312012",
+            "https://squirrelchasers.ingest.sentry.io.evil.test/12312012",
+            True,
+        ),
+        (
+            "https://dogsarebadatkeepingsecrets@squirrelchasers.ingest.sentry.io/12312012",
+            "https://squirrelchasers.ingest.sentry.io@attacker.test/12312012",
+            True,
+        ),
+        (
+            "https://dogsarebadatkeepingsecrets@squirrelchasers.ingest.sentry.io/12312012",
+            "https://attacker.test/?next=squirrelchasers.ingest.sentry.io",
+            True,
+        ),
         (
             "https://dogsarebadatkeepingsecrets@squirrelchasers.ingest.sentry.io/12312012",
             "http://ingest.sentry.io/12312012",