{"id":"CVE-2026-44226","aliases":["PYSEC-2026-2993"],"url":"https://o3.security/vulnerability/CVE-2026-44226","summary":"PyLoad vulnerable to unauthenticated traceback disclosure via global exception handler in WebUI","details":"### Summary\n`pyload-ng` WebUI returns full Python traceback details to clients on unhandled exceptions.\n\nBecause `/web/` is reachable without authentication and renders attacker-controlled template names, an unauthenticated user can reliably trigger a server exception (for example by requesting a non-existent template) and receive internal stack traces in the HTTP response.\n\n### Details\nThe issue is caused by the combination of:\n\n1. Unauthenticated template-render route:\n- `src/pyload/webui/app/blueprints/app_blueprint.py:32-36`\n - `@bp.route(\"/web/\", endpoint=\"web\")`\n - `data = render_template(filename)` with user-controlled `filename`\n - no `@login_required(...)` on this route\n\n2. Global exception handler exposes traceback to response:\n- `src/pyload/webui/app/handlers.py:14-27`\n - `tb = traceback.format_exc()`\n - `messages.extend(tb.split('\\n'))`\n - returned in rendered error page for all exceptions\n\n3. Error page renders all `messages`:\n- `src/pyload/webui/app/themes/modern/templates/base.html:217-219`\n - loops over `messages` and prints them in response HTML\n\nSo any unhandled exception can disclose internal implementation details (stack frames, source paths, exception metadata) to remote unauthenticated clients. \n\nThis is a core behavior issue in default WebUI error handling\n\n### PoC\n```python\n#!/usr/bin/env python3\nfrom __future__ import annotations\n\nimport re\nimport shutil\nimport tempfile\nimport traceback\nfrom pathlib import Path\n\n\nROOT = Path(__file__).resolve().parent / \"pyload\" / \"src\" / \"pyload\"\n\n\ndef read_text(rel: str) -> str:\n return (ROOT / rel).read_text(encoding=\"utf-8\")\n\n\ndef route_has_no_login_required(app_blueprint: str) -> bool:\n m = re.search(\n r'@bp\\\\.route\\\\(\"/web/\", endpoint=\"web\"\\\\)\\\\s*'\n r\"def render\\\\(filename\\\\):(?P.*?)(?:\\\\n\\\\n@bp\\\\.route|\\\\Z)\",\n app_blueprint,\n re.DOTALL,\n )\n if not m:\n return False\n block_start = max(0, m.start() - 200)\n block = app_blueprint[block_start:m.end()]\n return \"@login_required(\" not in block\n\n\ndef main() -> None:\n workdir = Path(tempfile.mkdtemp(prefix=\"pyload-traceback-infoleak-\"))\n try:\n app_blueprint = read_text(\"webui/app/blueprints/app_blueprint.py\")\n handlers = read_text(\"webui/app/handlers.py\")\n base_template = read_text(\"webui/app/themes/modern/templates/base.html\")\n\n unauth_web_route = '/web/' in app_blueprint and route_has_no_login_required(app_blueprint)\n user_controlled_template_name = \"render_template(filename)\" in app_blueprint\n handler_uses_traceback = \"traceback.format_exc()\" in handlers\n handler_appends_trace = \"messages.extend(tb.split('\\\\n'))\" in handlers\n global_exception_handler = \"(Exception, handle_exception_error)\" in handlers\n template_renders_messages = \"{% for message in messages %}\" in base_template and \"{{message}}\" in base_template\n\n leaked_traceback_keyword = False\n leaked_exception_type = False\n try:\n raise RuntimeError(\"forced-poc-error\")\n except Exception:\n tb = traceback.format_exc()\n messages = [f\"Error 500: forced-poc-error\"]\n messages.extend(tb.split(\"\\\\n\"))\n joined = \"\\\\n\".join(messages)\n leaked_traceback_keyword = \"Traceback (most recent call last)\" in joined\n leaked_exception_type = \"RuntimeError: forced-poc-error\" in joined\n\n repro_success = all(\n [\n unauth_web_route,\n user_controlled_template_name,\n handler_uses_traceback,\n handler_appends_trace,\n global_exception_handler,\n template_renders_messages,\n leaked_traceback_keyword,\n leaked_exception_type,\n ]\n )\n\n print(\"unauth_web_route=\", unauth_web_route)\n print(\"user_controlled_template_name=\", user_controlled_template_name)\n print(\"handler_uses_traceback=\", handler_uses_traceback)\n print(\"handler_appends_trace=\", handler_appends_trace)\n print(\"global_exception_handler=\", global_exception_handler)\n print(\"template_renders_messages=\", template_renders_messages)\n print(\"leaked_traceback_keyword=\", leaked_traceback_keyword)\n print(\"leaked_exception_type=\", leaked_exception_type)\n print(\"traceback_infoleak_repro_success=\", repro_success)\n finally:\n shutil.rmtree(workdir, ignore_errors=True)\n print(\"cleanup_done=True\")\n\n\nif __name__ == \"__main__\":\n main()\n```\n\nObserved result:\n```text\nunauth_web_route= True\nuser_controlled_template_name= True\nhandler_uses_traceback= True\nhandler_appends_trace= True\nglobal_exception_handler= True\ntemplate_renders_messages= True\nleaked_traceback_keyword= True\nleaked_exception_type= True\ntraceback_infoleak_repro_success= True\ncleanup_done=True\n```\n\n### Impact\n- Vulnerability type: Information disclosure (stack trace / internal path leakage).\n- Attack surface: unauthenticated WebUI request path.\n- Exposes internal error details that help attackers map application internals and improve exploit reliability for follow-on attacks.","published":"2026-05-06T17:54:20Z","modified":"2026-07-13T16:43:06.837973926Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"},"epss":{"score":0.00336,"percentile":0.26454,"asOf":"2026-08-14"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"pyload-ng","fixedVersion":"0.5.0b3.dev100"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/pyload/pyload/security/advisories/GHSA-c3gc-9pf2-84gg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44226"},{"type":"PACKAGE","url":"https://github.com/pyload/pyload"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-13T16:43:06.837973926Z"}}