PYSEC-2026-3600
Vulnerability from pysec - Published: 2026-08-04 11:34 - Updated: 2026-08-04 13:36Summary
The 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:
- HTTP path (
proxy_terminal) setsheaders['X-User-Id'] = user.id. Upstreams that trustX-User-Idas identity receive it unsigned, so an attacker who can reach the upstream by other means (directly, a compromised peer, SSRF) can spoof it. - WebSocket path (
ws_terminal) is exploitable through Open WebUI itself, with no "other means" required. It interpolates the path parametersession_iddirectly into the upstream URL and then appends?user_id=<caller>:
python
upstream_url = f'{ws_base}/p/{policy_id}/api/terminals/{session_id}'
upstream_url += f'?{urllib.parse.urlencode({"user_id": user.id})}'
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.
Technical Details
The 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.
Impact
A 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.
Appendix: Affected code
backend/open_webui/routers/terminals.py—proxy_terminalsetsheaders['X-User-Id'] = user.idwith no signature.backend/open_webui/routers/terminals.py—ws_terminalbuilds the upstream URL from an unvalidated, unencodedsession_idand appendsuser_idas a query parameter, allowing query injection.
Appendix: Consolidation
Per 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:
- @smoke-wolf (earliest filing) — the
X-User-IdHTTP-path identity is forwarded without integrity binding, spoofable where the upstream trusts the header. - @rexpository — the
ws_terminalsession_idquery-injection vector, proving the forwardeduser_idis spoofable through the Open WebUI proxy itself, with no "reach the upstream by other means" precondition.
Appendix: Recommended fix
- Validate and URL-encode
session_idbefore 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. - 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.
| Name | purl | open-webui | pkg:pypi/open-webui |
|---|
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "open-webui",
"purl": "pkg:pypi/open-webui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.10.0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.1.124",
"0.1.125",
"0.2.0",
"0.2.1",
"0.2.2",
"0.2.3",
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"0.3.10",
"0.3.12",
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"0.3.17.dev3",
"0.3.17.dev4",
"0.3.17.dev5",
"0.3.18",
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"0.3.2",
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"0.4.5",
"0.4.6",
"0.4.6.dev1",
"0.4.7",
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"0.6.16",
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"0.6.2",
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"0.6.22",
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"0.6.32",
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"0.6.7",
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"0.7.0",
"0.7.1",
"0.7.2",
"0.8.0",
"0.8.1",
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"0.8.11",
"0.8.12",
"0.8.2",
"0.8.3",
"0.8.4",
"0.8.5",
"0.8.6",
"0.8.7",
"0.8.8",
"0.8.9",
"0.9.0",
"0.9.1",
"0.9.2",
"0.9.3",
"0.9.4",
"0.9.5",
"0.9.6"
]
}
],
"aliases": [
"CVE-2026-59224",
"GHSA-j657-m4c4-24jq"
],
"details": "## Summary\n\nThe terminal proxy in `backend/open_webui/routers/terminals.py` forwards the Open WebUI user\u0027s 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[\u0027X-User-Id\u0027] = 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=\u003ccaller\u003e`:\n\n ```python\n upstream_url = f\u0027{ws_base}/p/{policy_id}/api/terminals/{session_id}\u0027\n upstream_url += f\u0027?{urllib.parse.urlencode({\"user_id\": user.id})}\u0027\n ```\n\n`session_id` is neither validated nor URL-encoded (the HTTP sibling runs `_sanitize_proxy_path`; this path runs nothing). An encoded `?`/`\u0026` smuggled through `session_id` survives Open WebUI\u0027s 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\u0027s 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\u0027s identity to the upstream backend coordinator. On backend coordinator-backed (`policy_id`) servers that scope terminal containers by `user_id`, this reaches another user\u0027s 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\u0027s 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` \u2014 `proxy_terminal` sets `headers[\u0027X-User-Id\u0027] = user.id` with no signature.\n- `backend/open_webui/routers/terminals.py` \u2014 `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) \u2014 the `X-User-Id` HTTP-path identity is forwarded without integrity binding, spoofable where the upstream trusts the header.\n- **@rexpository** \u2014 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 `?`, `#`, `\u0026`, `/`, `%`, 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.",
"id": "PYSEC-2026-3600",
"modified": "2026-08-04T13:36:26.549304Z",
"published": "2026-08-04T11:34:43.290734Z",
"references": [
{
"type": "WEB",
"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": "WEB",
"url": "https://github.com/open-webui/open-webui/pull/26042"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/commit/5f3a628a8d291bb5d33e1a0b0c89fb62a2927934"
},
{
"type": "PACKAGE",
"url": "https://github.com/open-webui/open-webui"
},
{
"type": "WEB",
"url": "https://github.com/open-webui/open-webui/releases/tag/v0.10.0"
},
{
"type": "PACKAGE",
"url": "https://pypi.org/project/open-webui"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-j657-m4c4-24jq"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"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)"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.