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fix(platforms): block image upload redirects to private URLs #62932

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fix(platforms): block image upload redirects to private URLs #62932

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176 changes: 112 additions & 64 deletions plugins/platforms/discord/adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@
from collections import defaultdict
from contextlib import suppress
from typing import Callable, Dict, List, Optional, Any, Tuple
from urllib.parse import urljoin

logger = logging.getLogger(__name__)

Expand Down Expand Up @@ -60,6 +61,8 @@ def __init__(self, id: int) -> None: # noqa: A002 - matches discord API
"non_conversational",
"non_conversational_history",
})
_DISCORD_IMAGE_REDIRECT_STATUSES = {301, 302, 303, 307, 308}
_DISCORD_IMAGE_MAX_REDIRECTS = 10
# Upgrade-bridge fallback only. The primary mechanism is the persisted
# non-conversational message-ID set populated from explicitly marked sends
# (metadata["non_conversational"]). These regexes exist solely to recognize
Expand Down Expand Up @@ -128,6 +131,43 @@ def __init__(self, id: int) -> None: # noqa: A002 - matches discord API
from tools.url_safety import is_safe_url


async def _read_url_image_with_redirect_guard(
session: Any,
url: str,
*,
timeout: Any,
request_kwargs: Dict[str, Any],
) -> Tuple[int, bytes, Dict[str, str]]:
"""Read an image URL while re-checking every redirect target for SSRF."""
current_url = url
for _ in range(_DISCORD_IMAGE_MAX_REDIRECTS + 1):
if not is_safe_url(current_url):
raise ValueError("Blocked unsafe image URL redirect")

async with session.get(
current_url,
timeout=timeout,
allow_redirects=False,

@teknium1 teknium1 Jul 12, 2026

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aiohttp headers are case-insensitive, but converting them to dict makes this subsequent headers.get("location") lookup case-sensitive. Preserve the original header mapping or normalize keys; otherwise normal Location headers can make safe redirects fail as HTTP 302.

**request_kwargs,
) as resp:
raw_headers = getattr(resp, "headers", {}) or {}
headers = {str(key).lower(): value for key, value in dict(raw_headers).items()}
status = int(getattr(resp, "status", 0))
if status in _DISCORD_IMAGE_REDIRECT_STATUSES:
location = headers.get("location")
if not location:
return status, b"", headers
next_url = urljoin(current_url, str(location))
if not is_safe_url(next_url):
raise ValueError("Blocked redirect to private/internal address")
current_url = next_url
continue

return status, await resp.read(), headers

raise ValueError("Too many image URL redirects")


def _truncate_discord_component_text(text: str, limit: int) -> str:
"""Return text within Discord's UTF-16 component field budget."""
return _prefix_within_utf16_limit(str(text or ""), max(0, limit))
Expand Down Expand Up @@ -2531,25 +2571,27 @@ async def send_multiple_images(
_sess_kw, _req_kw = proxy_kwargs_for_aiohttp(_proxy)
if aiohttp_session is None:
aiohttp_session = _aiohttp.ClientSession(**_sess_kw)
async with aiohttp_session.get(
image_url, timeout=_aiohttp.ClientTimeout(total=30), **_req_kw,
) as resp:
if resp.status != 200:
logger.warning(
"[%s] Failed to download image (HTTP %d) in batch: %s",
self.name, resp.status, image_url[:80],
)
continue
data = await resp.read()
ct = resp.headers.get("content-type", "image/png")
ext = "png"
if "jpeg" in ct or "jpg" in ct:
ext = "jpg"
elif "gif" in ct:
ext = "gif"
elif "webp" in ct:
ext = "webp"
files.append(_discord_mod.File(_io.BytesIO(data), filename=f"image_{len(files)}.{ext}"))
status, data, headers = await _read_url_image_with_redirect_guard(
aiohttp_session,
image_url,
timeout=_aiohttp.ClientTimeout(total=30),
request_kwargs=_req_kw,
)
if status != 200:
logger.warning(
"[%s] Failed to download image (HTTP %d) in batch: %s",
self.name, status, image_url[:80],
)
continue
ct = headers.get("content-type", "image/png")
ext = "png"
if "jpeg" in ct or "jpg" in ct:
ext = "jpg"
elif "gif" in ct:
ext = "gif"
elif "webp" in ct:
ext = "webp"
files.append(_discord_mod.File(_io.BytesIO(data), filename=f"image_{len(files)}.{ext}"))
except Exception as dl_err:
logger.warning("[%s] Download failed for %s: %s", self.name, image_url[:80], dl_err)
continue
Expand Down Expand Up @@ -3666,37 +3708,40 @@ async def send_image(
_proxy = resolve_proxy_url(platform_env_var="DISCORD_PROXY")
_sess_kw, _req_kw = proxy_kwargs_for_aiohttp(_proxy)
async with aiohttp.ClientSession(**_sess_kw) as session:
async with session.get(image_url, timeout=aiohttp.ClientTimeout(total=30), **_req_kw) as resp:
if resp.status != 200:
raise Exception(f"Failed to download image: HTTP {resp.status}")

image_data = await resp.read()

# Determine filename from URL or content type
content_type = resp.headers.get("content-type", "image/png")
ext = "png"
if "jpeg" in content_type or "jpg" in content_type:
ext = "jpg"
elif "gif" in content_type:
ext = "gif"
elif "webp" in content_type:
ext = "webp"

import io
file = discord.File(io.BytesIO(image_data), filename=f"image.{ext}")

if self._is_forum_parent(channel):
return await self._forum_post_file(
channel,
content=(caption or "").strip(),
file=file,
)
status, image_data, headers = await _read_url_image_with_redirect_guard(
session,
image_url,
timeout=aiohttp.ClientTimeout(total=30),
request_kwargs=_req_kw,
)
if status != 200:
raise Exception(f"Failed to download image: HTTP {status}")

# Determine filename from URL or content type
content_type = headers.get("content-type", "image/png")
ext = "png"
if "jpeg" in content_type or "jpg" in content_type:
ext = "jpg"
elif "gif" in content_type:
ext = "gif"
elif "webp" in content_type:
ext = "webp"

import io
file = discord.File(io.BytesIO(image_data), filename=f"image.{ext}")

msg = await channel.send(
content=caption if caption else None,
if self._is_forum_parent(channel):
return await self._forum_post_file(
channel,
content=(caption or "").strip(),
file=file,
)
return SendResult(success=True, message_id=str(msg.id))

msg = await channel.send(
content=caption if caption else None,
file=file,
)
return SendResult(success=True, message_id=str(msg.id))

except ImportError:
logger.warning(
Expand Down Expand Up @@ -3745,27 +3790,30 @@ async def send_animation(
_proxy = resolve_proxy_url(platform_env_var="DISCORD_PROXY")
_sess_kw, _req_kw = proxy_kwargs_for_aiohttp(_proxy)
async with aiohttp.ClientSession(**_sess_kw) as session:
async with session.get(animation_url, timeout=aiohttp.ClientTimeout(total=30), **_req_kw) as resp:
if resp.status != 200:
raise Exception(f"Failed to download animation: HTTP {resp.status}")

animation_data = await resp.read()

import io
file = discord.File(io.BytesIO(animation_data), filename="animation.gif")
status, animation_data, _headers = await _read_url_image_with_redirect_guard(
session,
animation_url,
timeout=aiohttp.ClientTimeout(total=30),
request_kwargs=_req_kw,
)
if status != 200:
raise Exception(f"Failed to download animation: HTTP {status}")

if self._is_forum_parent(channel):
return await self._forum_post_file(
channel,
content=(caption or "").strip(),
file=file,
)
import io
file = discord.File(io.BytesIO(animation_data), filename="animation.gif")

msg = await channel.send(
content=caption if caption else None,
if self._is_forum_parent(channel):
return await self._forum_post_file(
channel,
content=(caption or "").strip(),
file=file,
)
return SendResult(success=True, message_id=str(msg.id))

msg = await channel.send(
content=caption if caption else None,
file=file,
)
return SendResult(success=True, message_id=str(msg.id))

except ImportError:
logger.warning(
Expand Down
5 changes: 4 additions & 1 deletion plugins/platforms/slack/adapter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@
is_host_excluded_by_no_proxy,
resolve_proxy_url,
safe_url_for_log,
_ssrf_redirect_guard,
cache_document_from_bytes,
cache_video_from_bytes,
)
Expand Down Expand Up @@ -1749,7 +1750,9 @@ async def send_multiple_images(
initial_comment_parts: List[str] = []
try:
async with _httpx.AsyncClient(
timeout=30.0, follow_redirects=True
timeout=30.0,
follow_redirects=True,
event_hooks={"response": [_ssrf_redirect_guard]},
) as http_client:
for image_url, alt_text in chunk:
if alt_text:
Expand Down
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