{"id":"CVE-2026-59224","aliases":["GHSA-j657-m4c4-24jq","PYSEC-2026-3600"],"url":"https://o3.security/vulnerability/CVE-2026-59224","summary":"Open WebUI: Terminal proxy forwards a spoofable, integrity-unbound user identity to the upstream (X-User-Id header and ws_terminal session_id query injection)","details":"## Summary\n\nThe terminal proxy in `backend/open_webui/routers/terminals.py` forwards the Open WebUI user's identity to the upstream terminal server / backend coordinator as an authorization claim, with no cryptographic binding to the session that produced it. The forwarded identity is attacker-influenceable on both proxy paths:\n\n1. **HTTP path (`proxy_terminal`)** sets `headers['X-User-Id'] = user.id`. Upstreams that trust `X-User-Id` as identity receive it unsigned, so an attacker who can reach the upstream by other means (directly, a compromised peer, SSRF) can spoof it.\n2. **WebSocket path (`ws_terminal`)** is exploitable through Open WebUI itself, with no \"other means\" required. It interpolates the path parameter `session_id` directly into the upstream URL and then appends `?user_id=<caller>`:\n\n   ```python\n   upstream_url = f'{ws_base}/p/{policy_id}/api/terminals/{session_id}'\n   upstream_url += f'?{urllib.parse.urlencode({\"user_id\": user.id})}'\n   ```\n\n`session_id` is neither validated nor URL-encoded (the HTTP sibling runs `_sanitize_proxy_path`; this path runs nothing). An encoded `?`/`&` smuggled through `session_id` survives Open WebUI's single decode and is re-decoded by the upstream, injecting an attacker-chosen `user_id` ahead of the appended one. Query parsing binds the first occurrence, so the backend coordinator resolves the spoofed user's terminal scope.\n\n## Technical Details\n\nThe forwarded terminal identity is a bearer-style authorization claim with no integrity binding, and on the WebSocket path it is additionally injectable because `session_id` is concatenated into the URL without encoding or delimiter validation.\n\n## Impact\n\nA normal authenticated user can make the terminal proxy present another user's identity to the upstream backend coordinator. On backend coordinator-backed (`policy_id`) servers that scope terminal containers by `user_id`, this reaches another user's terminal scope; combined with a known active session ID (for example a chat-scoped session ID surfaced through a shared chat), it allows attaching to that user's live PTY. The HTTP-path variant additionally allows identity spoofing at the upstream tier for any deployment whose upstream trusts `X-User-Id`.\n\n## Appendix: Affected code\n\n- `backend/open_webui/routers/terminals.py` — `proxy_terminal` sets `headers['X-User-Id'] = user.id` with no signature.\n- `backend/open_webui/routers/terminals.py` — `ws_terminal` builds the upstream URL from an unvalidated, unencoded `session_id` and appends `user_id` as a query parameter, allowing query injection.\n\n## Appendix: Consolidation\n\nPer the Report Handling policy, this consolidates independent reports of the same root cause (the forwarded terminal identity is spoofable / not integrity-bound) into the earliest filing:\n\n- **@smoke-wolf** (earliest filing) — the `X-User-Id` HTTP-path identity is forwarded without integrity binding, spoofable where the upstream trusts the header.\n- **@rexpository** — the `ws_terminal` `session_id` query-injection vector, proving the forwarded `user_id` is spoofable through the Open WebUI proxy itself, with no \"reach the upstream by other means\" precondition.\n\n## Appendix: Recommended fix\n\n- Validate and URL-encode `session_id` before building the upstream URL (`urllib.parse.quote(session_id, safe=\"\")`; reject `?`, `#`, `&`, `/`, `%`, backslash, control characters). Build the query string with a URL builder so attacker-controlled path content cannot precede it.\n- Bind the forwarded identity instead of passing a raw `user_id` / `X-User-Id`: emit a short-lived signed claim (for example HS256 over `{uid, iat, aud:server_id}` with a key shared only with the specific upstream) and verify it upstream.","published":"2026-07-09T17:09:31.980Z","modified":"2026-08-12T03:51:39.901580199Z","cvss":{"score":8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H"},"epss":{"score":0.00391,"percentile":0.32877,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"open-webui","fixedVersion":"0.10.0"}],"fix":{"url":"https://github.com/open-webui/open-webui/commit/5f3a628a8d291bb5d33e1a0b0c89fb62a2927934","label":"open-webui/open-webui@5f3a628"},"references":[{"type":"WEB","url":"https://github.com/open-webui/open-webui/releases/tag/v0.10.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59224.json"},{"type":"ADVISORY","url":"https://github.com/open-webui/open-webui/security/advisories/GHSA-j657-m4c4-24jq"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59224"},{"type":"FIX","url":"https://github.com/open-webui/open-webui/commit/5f3a628a8d291bb5d33e1a0b0c89fb62a2927934"},{"type":"FIX","url":"https://github.com/open-webui/open-webui/pull/26042"},{"type":"PACKAGE","url":"https://github.com/open-webui/open-webui"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:39.901580199Z"}}