CVE-2026-54017

The terminal-server reverse proxy in backend/open_webui/routers/terminals.py does not fully confine the user-controlled path segment before forwarding it to an admin-configured terminal server. An authenticated user who has been granted access to a terminal server can craft path values containing encoded ../ traversal sequences that escape the intended path (or policy) scope on that server, reaching unintended endpoints and files on the terminal-server host. Where the terminal server fans requests out to internal services, this also gives SSRF-style reach into those services.

This is a separate code path from the /api/v1/retrieval/process/web SSRF (GHSA-c6xv-rcvw-v685), with its own input. Two distinct vectors are consolidated here:

1. Raw path forwarding / single-encoded traversal (original report).
2. A bypass of the subsequently-added _sanitize_proxy_path mitigation using double-encoded dots (%252e%252e).

The attacker-controlled input is the request path, supplied by the non-admin user, not anything an administrator configures, so this is not an admin-trust / Rule-9 situation.

Affected code

The proxy route forwards an arbitrary trailing path to the configured terminal server:

# routers/terminals.py
@router.api_route('/{server_id}/{path:path}', methods=PROXY_METHODS)
async def proxy_terminal(server_id, path, request, user=Depends(get_verified_user)):
    ...
    safe_path = _sanitize_proxy_path(path)
    if safe_path is None:
        return JSONResponse({'error': 'Invalid path'}, status_code=400)
    target_url = f'{base_url}/{safe_path}'
    policy_id = connection.get('policy_id')
    if policy_id:
        target_url = f'{base_url}/p/{policy_id}/{safe_path}'

Access requires has_connection_access(user, connection, ...), i.e. a non-admin user the administrator has granted to that terminal server.

Vector 1, single-encoded traversal (original)

The path was originally concatenated to the base URL with no sanitization (target_url = f"{base_url}/{path}"), so single-encoded traversal escaped the intended scope:

GET /api/v1/terminals/server1/..%2F..%2F..%2Finternal-api/secrets
# proxied to: {base_url}/../../../internal-api/secrets

This vector is closed at HEAD: _sanitize_proxy_path now URL-decodes once, runs posixpath.normpath, strips leading slashes, and rejects results beginning with .. (unquote('..%2F..%2F') -> '../../' -> normpath -> '../..' -> rejected).

Vector 2, double-encoded bypass of _sanitize_proxy_path

_sanitize_proxy_path decodes the path only once before the .. check, so a double-encoded payload survives:

def _sanitize_proxy_path(path: str) -> str | None:
    decoded = unquote(path)                 # single decode pass only
    normalized = posixpath.normpath(decoded)
    cleaned = normalized.lstrip('/')
    if cleaned.startswith('..') or cleaned == '.':
        return None
    ...

unquote('%252e%252e/secret') yields %2e%2e/secret (not ..), which normpath leaves unchanged and which does not start with .., so it passes the check. The proxy then forwards {base_url}/%2e%2e/secret, and the upstream terminal server decodes %2e%2e into .. and resolves the traversal the check was meant to prevent.

GET /api/v1/terminals/server1/%252e%252e/%252e%252e/sensitive-file
# passes _sanitize_proxy_path as %2e%2e/%2e%2e/sensitive-file
# upstream decodes -> ../../sensitive-file

The policy_id form ({base_url}/p/{policy_id}/{safe_path}) is the higher-impact target: traversal escapes the policy namespace and reaches other policies or the terminal-server root.

Credits

• Tulgaaaaaaaa, original report (terminal-proxy path SSRF / single-encoded traversal).
• sermikr0, double-encoded (%252e%252e) bypass of the _sanitize_proxy_path mitigation.

An authenticated user with access to a terminal server can escape the intended path/policy scope on that server, reaching unintended endpoints and files, and, where the terminal server routes onward to internal services, reach those services. CWE-22 (Path Traversal) and CWE-918 (SSRF).

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2026-54017 has a CVSS score of 7.7 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.9.6); upgrading removes the vulnerable code path.

Kodem intelligence

Decode the proxy path until it is stable before normalising and checking, so no depth of encoding can smuggle a traversal sequence past the check to be re-decoded upstream:

decoded = path
for _ in range(8):
    once = unquote(decoded)
    if once == decoded:
        break
    decoded = once
normalized = posixpath.normpath(decoded)
cleaned = normalized.lstrip('/')
if cleaned.startswith('..') or cleaned == '.':
    return None

This rejects %2e%2e, %252e%252e, %25252e%25252e, ..%2f..%2f, etc., while leaving legitimate paths (including singly-encoded characters such as %20) intact.

1. What is CVE-2026-54017? CVE-2026-54017 is a high-severity path traversal vulnerability in open-webui (pip), affecting versions <= 0.9.5. It is fixed in 0.9.6. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2026-54017? CVE-2026-54017 has a CVSS score of 7.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of open-webui are affected by CVE-2026-54017? open-webui (pip) versions <= 0.9.5 is affected.
4. Is there a fix for CVE-2026-54017? Yes. CVE-2026-54017 is fixed in 0.9.6. Upgrade to this version or later.
5. Is CVE-2026-54017 exploitable, and should I be worried? Whether CVE-2026-54017 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-54017 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-54017? Upgrade open-webui to 0.9.6 or later.