diff --git a/files/helpers/sanitize.py b/files/helpers/sanitize.py
index 89b5d5b594..607d35a19d 100644
--- a/files/helpers/sanitize.py
+++ b/files/helpers/sanitize.py
@@ -81,8 +81,17 @@ def allowed_attributes(tag, name, value):
url_re = build_url_re(tlds=TLDS, protocols=['http', 'https'])
def callback(attrs, new=False):
+ if (None, "href") not in attrs:
+ return # Incorrect tag
+
href = attrs[(None, "href")]
+ # \ in href right after / makes most browsers ditch site hostname and allows for a host injection bypassing the check, see cool
+ if "\\" in href:
+ attrs["_text"] = href # Laugh at this user
+ del attrs[(None, "href")] # Make unclickable and reset harmful payload
+ return attrs
+
if not href.startswith('/') and not href.startswith(f'{SITE_FULL}/'):
attrs[(None, "target")] = "_blank"
attrs[(None, "rel")] = "nofollow noopener noreferrer"
@@ -128,6 +137,7 @@ def render_emoji(html, regexp, edit, marseys_used=set(), b=False):
if emoji_html:
+ marseys_used.add(emoji)
html = re.sub(f'(?