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fix(security): sanitize HTML in chat UI to prevent XSS injection #3820

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fix(security): sanitize HTML in chat UI to prevent XSS injection #3820

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dcdc46e
fix(security): sanitize HTML in chat UI to prevent XSS injection
xr843 Mar 21, 2026
3020727
style: fix formatting
xr843 Mar 21, 2026
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12 changes: 9 additions & 3 deletions fastchat/conversation.py
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@
import base64
import dataclasses
from enum import auto, IntEnum
import html
from io import BytesIO
import os
from typing import List, Any, Dict, Union, Tuple
Expand Down Expand Up @@ -370,13 +371,18 @@ def to_gradio_chatbot(self):
msg, images = msg
image = images[0] # Only one image on gradio at one time
if image.image_format == ImageFormat.URL:
img_str = f'<img src="{image.url}" alt="user upload image" />'
img_str = f'<img src="{html.escape(image.url)}" alt="user upload image" />'
elif image.image_format == ImageFormat.BYTES:
img_str = f'<img src="data:image/{image.filetype};base64,{image.base64_str}" alt="user upload image" />'
msg = img_str + msg.replace("<image>\n", "").strip()
img_str = f'<img src="data:image/{html.escape(image.filetype)};base64,{image.base64_str}" alt="user upload image" />'
msg = img_str + html.escape(msg.replace("<image>\n", "").strip())
else:
if msg is not None:
msg = html.escape(msg)

ret.append([msg, None])
else:
if msg is not None:
msg = html.escape(msg)
ret[-1][-1] = msg
return ret

Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_block_arena_anony.py
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Expand Up @@ -480,6 +480,7 @@ def build_side_by_side_ui_anony(models):
elem_id="chatbot",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_block_arena_named.py
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,7 @@ def build_side_by_side_ui_named(models):
elem_id=f"chatbot",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_block_arena_vision.py
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Original file line number Diff line number Diff line change
Expand Up @@ -356,6 +356,7 @@ def build_single_vision_language_model_ui(
label="Scroll down and start chatting",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_block_arena_vision_anony.py
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Original file line number Diff line number Diff line change
Expand Up @@ -432,6 +432,7 @@ def build_side_by_side_vision_ui_anony(context: Context, random_questions=None):
elem_id="chatbot",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_block_arena_vision_named.py
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Original file line number Diff line number Diff line change
Expand Up @@ -372,6 +372,7 @@ def build_side_by_side_vision_ui_named(context: Context, random_questions=None):
elem_id=f"chatbot",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
1 change: 1 addition & 0 deletions fastchat/serve/gradio_web_server.py
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Original file line number Diff line number Diff line change
Expand Up @@ -927,6 +927,7 @@ def build_single_model_ui(models, add_promotion_links=False):
label="Scroll down and start chatting",
height=650,
show_copy_button=True,
sanitize_html=True,
latex_delimiters=[
{"left": "$", "right": "$", "display": False},
{"left": "$$", "right": "$$", "display": True},
Expand Down
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