diff --git a/CHANGES/+file_url_sanitation.bugfix b/CHANGES/+file_url_sanitation.bugfix
new file mode 100644
index 00000000000..43b2827dcb7
--- /dev/null
+++ b/CHANGES/+file_url_sanitation.bugfix
@@ -0,0 +1 @@
+Fixed file downloader path sanitation. CVE-2026-90959
diff --git a/pulpcore/app/serializers/repository.py b/pulpcore/app/serializers/repository.py
index 8a6d669775e..24377375cab 100644
--- a/pulpcore/app/serializers/repository.py
+++ b/pulpcore/app/serializers/repository.py
@@ -282,24 +282,28 @@ def validate_url(self, url):
                 )
             )
 
-        if not url.lower().startswith("file://"):
-            return url
-
-        user_path = url[7:]
-        if not os.path.isabs(user_path):
-            raise serializers.ValidationError(
-                _("The path '{}' needs to be an absolute pathname.").format(user_path)
-            )
+        if parsed_url.scheme == "file":
+            user_path = parsed_url.path
+            if not os.path.isabs(user_path):
+                raise serializers.ValidationError(
+                    _("The path '{}' needs to be an absolute pathname.").format(user_path)
+                )
+            if user_path.rstrip("/") != os.path.normpath(user_path):
+                raise serializers.ValidationError(_("The path '{}' is not normalized."))
 
-        user_provided_realpath = os.path.realpath(user_path)
+            user_provided_realpath = os.path.realpath(user_path)
 
-        for allowed_path in settings.ALLOWED_IMPORT_PATHS:
-            if user_provided_realpath.startswith(allowed_path):
-                return url
+            if not any(
+                user_provided_realpath.startswith(allowed_path)
+                for allowed_path in settings.ALLOWED_IMPORT_PATHS
+            ):
+                raise serializers.ValidationError(
+                    _("The path '{}' does not start with any of the allowed import paths").format(
+                        user_path
+                    )
+                )
 
-        raise serializers.ValidationError(
-            _("The path '{}' does not start with any of the allowed import paths").format(user_path)
-        )
+        return url
 
     def validate_proxy_url(self, value):
         """
diff --git a/pulpcore/download/file.py b/pulpcore/download/file.py
index 4e72570cdeb..9fa26697929 100644
--- a/pulpcore/download/file.py
+++ b/pulpcore/download/file.py
@@ -2,6 +2,7 @@
 from urllib.parse import urlparse
 
 import aiofiles
+from rest_framework.serializers import ValidationError
 
 from .base import BaseDownloader, DownloadResult
 
@@ -35,6 +36,9 @@ def __init__(self, url, *args, **kwargs):
 
         RemoteSerializer().validate_url(url)
         p = urlparse(url)
+        if p.scheme != "file":
+            raise ValidationError("Not a valid file url.")
+
         self._path = os.path.abspath(os.path.join(p.netloc, p.path))
         super().__init__(url, *args, **kwargs)
 
diff --git a/pulpcore/tests/unit/download/test_downloader_factory.py b/pulpcore/tests/unit/download/test_downloader_factory.py
index 9277fb82af2..900a0847456 100644
--- a/pulpcore/tests/unit/download/test_downloader_factory.py
+++ b/pulpcore/tests/unit/download/test_downloader_factory.py
@@ -1,9 +1,16 @@
 import pytest
 
+from pulpcore.app.util import get_domain
 from pulpcore.download.factory import DownloaderFactory
 from pulpcore.plugin.models import Remote
 
 
+@pytest.fixture(autouse=True)
+def mock_default_domain(db):
+    # Cache the domain in synchronous context before starting the tests.
+    get_domain()
+
+
 @pytest.mark.asyncio
 async def test_user_agent_header():
     remote = Remote(url="http://example.org/", name="foo")
diff --git a/pulpcore/tests/unit/download/test_downloader_file.py b/pulpcore/tests/unit/download/test_downloader_file.py
new file mode 100644
index 00000000000..1a78348e518
--- /dev/null
+++ b/pulpcore/tests/unit/download/test_downloader_file.py
@@ -0,0 +1,41 @@
+import pytest
+from rest_framework.serializers import ValidationError
+
+from pulpcore.download import FileDownloader
+
+
+@pytest.fixture
+def import_paths(settings):
+    settings.ALLOWED_IMPORT_PATHS = ["/static", "/var/www"]
+
+
+@pytest.mark.parametrize(
+    "url",
+    [
+        "file:///tmp/www",
+        "file:///tmp/www/",
+        "file:///tmp/www/a",
+        "file:///tmp/www/a/",
+    ],
+)
+def test_file_downloader_accepts_regular_file_urls(url, import_paths):
+    FileDownloader(url)
+
+
+@pytest.mark.parametrize(
+    "url",
+    [
+        "",
+        "...",
+        "/",
+        "file:///",
+        "file:.",
+        "file://var/www",
+        "file:///../../../../var/www",
+        "file:///var/www/../../../../etc/secrets",
+        "file:../../../../../../../etc/secrets",
+    ],
+)
+def test_file_downloader_rejects_path_traversal_attempts(url, import_paths):
+    with pytest.raises(ValidationError):
+        FileDownloader(url)