diff --git a/src/specify_cli/commands/bundle/__init__.py b/src/specify_cli/commands/bundle/__init__.py
index 224d63fc5f..d8fb22e511 100644
--- a/src/specify_cli/commands/bundle/__init__.py
+++ b/src/specify_cli/commands/bundle/__init__.py
@@ -765,7 +765,16 @@ def _download_manifest(resolved, *, offline: bool):
             f"Catalog entry '{resolved.entry.id}' has no download_url; cannot resolve "
             "its manifest."
         )
-    parsed = urlparse(url)
+    # A malformed authority (e.g. an unclosed IPv6 bracket ``https://[::1``)
+    # makes urlparse raise ValueError. Surface it as the documented
+    # BundlerError, like the sibling ``_validate_remote_url``, rather than
+    # leaking a raw ValueError past the callers, which only catch BundlerError.
+    try:
+        parsed = urlparse(url)
+    except ValueError:
+        raise BundlerError(
+            f"Catalog entry '{resolved.entry.id}' has a malformed download_url: {url}"
+        ) from None
     scheme = parsed.scheme.lower()
 
     # ``file://`` URLs and bare filesystem paths (including Windows drive paths
@@ -802,8 +811,17 @@ def _download_manifest(resolved, *, offline: bool):
 def _require_https(label: str, url: str) -> None:
     from urllib.parse import urlparse
 
-    parsed = urlparse(url)
-    is_localhost = parsed.hostname in ("localhost", "127.0.0.1", "::1")
+    # urlparse / hostname access raise ValueError on a malformed authority;
+    # keep the documented BundlerError contract (older Pythons surface this via
+    # the .hostname access below rather than at the urlparse call).
+    try:
+        parsed = urlparse(url)
+        hostname = parsed.hostname
+    except ValueError:
+        raise BundlerError(
+            f"Refusing to download {label}: URL is malformed: {url}"
+        ) from None
+    is_localhost = hostname in ("localhost", "127.0.0.1", "::1")
     if parsed.scheme != "https" and not (parsed.scheme == "http" and is_localhost):
         raise BundlerError(
             f"Refusing to download {label} over non-HTTPS URL: {url}"
diff --git a/tests/unit/test_bundle_download_url.py b/tests/unit/test_bundle_download_url.py
new file mode 100644
index 0000000000..6a53b9368b
--- /dev/null
+++ b/tests/unit/test_bundle_download_url.py
@@ -0,0 +1,42 @@
+"""Unit tests for malformed download-URL handling in bundle manifest resolution."""
+from __future__ import annotations
+
+from types import SimpleNamespace
+
+import pytest
+
+from specify_cli.bundler import BundlerError
+from specify_cli.commands.bundle import _download_manifest, _require_https
+
+_MALFORMED_URLS = [
+    "https://[::1",  # unclosed IPv6 bracket
+    "https://[not-an-ip]/bundle.yml",
+]
+
+
+@pytest.mark.parametrize("url", _MALFORMED_URLS)
+def test_download_manifest_rejects_malformed_url_cleanly(url):
+    """A malformed download_url must raise BundlerError, not a raw ValueError.
+
+    ``urlparse`` raises ``ValueError`` on a malformed authority (e.g. an
+    unclosed IPv6 bracket). The bundle CLI commands only catch BundlerError, so
+    a raw ValueError would escape as an uncaught traceback. Sibling of the
+    guarded ``_validate_remote_url`` (adapters) and the merged #3576 fix.
+    """
+    resolved = SimpleNamespace(
+        entry=SimpleNamespace(id="mybundle", download_url=url)
+    )
+    with pytest.raises(BundlerError):
+        _download_manifest(resolved, offline=True)
+
+
+@pytest.mark.parametrize("url", _MALFORMED_URLS)
+def test_require_https_rejects_malformed_url_cleanly(url):
+    """``_require_https`` must also surface BundlerError on a malformed authority.
+
+    On older Python versions the ValueError is raised at ``.hostname`` access
+    rather than at ``urlparse``, so guarding both keeps the contract across the
+    CI Python matrix.
+    """
+    with pytest.raises(BundlerError):
+        _require_https("bundle 'x'", url)