.

inbox.py

@@ -18,6 +18,7 @@ from languages import understood_post_language
 from like import update_likes_collection
 from reaction import update_reaction_collection
 from reaction import valid_emoji_content
+from utils import contains_invalid_actor_url_chars
 from utils import is_quote_toot
 from utils import acct_handle_dir
 from utils import is_account_dir
@@ -2756,13 +2757,16 @@ def _receive_announce(recent_posts_cache: {},
         # so that their avatar can be shown
         lookup_actor = None
         if post_json_object.get('attributedTo'):
-            if isinstance(post_json_object['attributedTo'], str):
-                lookup_actor = post_json_object['attributedTo']
+            attrib = post_json_object['attributedTo']
+            if isinstance(attrib, str):
+                if not contains_invalid_actor_url_chars(attrib):
+                    lookup_actor = attrib
         else:
             if has_object_dict(post_json_object):
                 if post_json_object['object'].get('attributedTo'):
                     attrib = post_json_object['object']['attributedTo']
                     if isinstance(attrib, str):
+                        if not contains_invalid_actor_url_chars(attrib):
                             lookup_actor = attrib
         if lookup_actor:
             if has_users_path(lookup_actor):

outbox.py

@@ -15,6 +15,7 @@ from posts import outbox_message_create_wrap
 from posts import save_post_to_box
 from posts import send_to_followers_thread
 from posts import send_to_named_addresses_thread
+from utils import contains_invalid_actor_url_chars
 from utils import get_attachment_property_value
 from utils import get_account_timezone
 from utils import has_object_string_type
@@ -321,6 +322,9 @@ def post_message_to_outbox(session, translate: {},
            '.' not in message_json['actor']:
             return False
 
+        if contains_invalid_actor_url_chars(message_json['actor']):
+            return False
+
         # sent by an actor on a local network address?
         if not allow_local_network_access:
             local_network_pattern_list = get_local_network_addresses()

person.py

@@ -44,6 +44,7 @@ from utils import get_attachment_property_value
 from utils import get_nickname_from_actor
 from utils import remove_html
 from utils import contains_invalid_chars
+from utils import contains_invalid_actor_url_chars
 from utils import replace_users_with_at
 from utils import remove_eol
 from utils import remove_domain_port
@@ -1776,6 +1777,12 @@ def valid_sending_actor(session, base_dir: str,
     # who sent this post?
     sending_actor = post_json_object['actor']
 
+    if not isinstance(sending_actor, str):
+        return False
+
+    if contains_invalid_actor_url_chars(sending_actor):
+        return False
+
     # If you are following them then allow their posts
     if is_following_actor(base_dir, nickname, domain, sending_actor):
         return True
@@ -1802,6 +1809,7 @@ def valid_sending_actor(session, base_dir: str,
         print('REJECT: no preferredUsername within actor ' + str(actor_json))
         return False
 
+    # is this a known spam actor?
     actor_spam_filter_filename = \
         acct_dir(base_dir, nickname, domain) + '/.reject_spam_actors'
     if not os.path.isfile(actor_spam_filter_filename):

utils.py

@@ -39,6 +39,12 @@ INVALID_CHARACTERS = (
     '卐', '卍', '࿕', '࿖', '࿗', '࿘', 'ϟϟ', '🏳️‍🌈🚫', '⚡⚡'
 )
 
+INVALID_ACTOR_URL_CHARACTERS = (
+    '
', '​', '<', '>', '%', '{', '}', '|', '\\', '^', '`',
+    '?', '#', '[', ']', '@', '!', '$', '&', "'", '(', ')',
+    '*', '+', ',', ';', '='
+)
+
 
 def _standardize_text_range(text: str,
                             range_start: int, range_end: int,
@@ -971,6 +977,16 @@ def contains_invalid_chars(json_str: str) -> bool:
     return False
 
 
+def contains_invalid_actor_url_chars(url: str) -> bool:
+    """Does the given actor url contain invalid characters?
+    """
+    for is_invalid in INVALID_ACTOR_URL_CHARACTERS:
+        if is_invalid in url:
+            return True
+
+    return contains_invalid_chars(url)
+
+
 def remove_invalid_chars(text: str) -> str:
     """Removes any invalid characters from a string
     """