Crawl4AI: Multiple Docker API Vulnerabilities - File Write, SSRF, Auth Bypass, XSS, JS Execution
Summary
Multiple security vulnerabilities in the Crawl4AI Docker API server affecting endpoints for crawling, markdown/LLM extraction, screenshots, PDFs, webhooks, monitoring, JavaScript execution, and configuration.
Vulnerabilities
1. Arbitrary File Write via /screenshot and /pdf (CWE-22, CVSS 9.1)
The output_path parameter accepts arbitrary filesystem paths with no validation. An attacker can overwrite server files (DoS) or write to any appuser-writable location.
Fix: Added validate_output_path() restricting writes to CRAWL4AI_OUTPUT_DIR (/tmp/crawl4ai-outputs by default). Added Pydantic field_validator rejecting .. traversal sequences.
2. SSRF via Webhook URL (CWE-918, CVSS 8.6)
Webhook URLs in /crawl/job and /llm/job accept internal/private IPs with no validation, enabling Server-Side Request Forgery against cloud metadata endpoints (169.254.169.254), internal services, and Docker networks.
Fix: Added validate_webhook_url() with blocklist for RFC 1918, loopback, link-local, cloud metadata IPs and hostnames. Validation at both job submission and send time. Explicit follow_redirects=False.
3. Authentication Bypass on Monitor Endpoints (CWE-306, CVSS 6.5)
The monitor router was mounted without token_dep dependency, making all monitoring endpoints (including destructive ones like /monitor/actions/cleanup) accessible without authentication.
Fix: Added dependencies=[Depends(token_dep)] to monitor router. Added explicit token check on WebSocket /monitor/ws endpoint.
4. Stored XSS in Monitor Dashboard (CWE-79, CVSS 6.1)
URLs and error messages rendered in the monitor dashboard via innerHTML without escaping, enabling stored XSS via crafted crawl URLs.
Fix: Server-side html.escape() on URL and error storage. Client-side escapeHtml() wrapper on all innerHTML template injections.
5. Arbitrary JavaScript Execution via /execute_js (CWE-94, CVSS 8.1)
The /execute_js endpoint accepts and executes arbitrary JavaScript in the server's browser with --disable-web-security enabled, combining arbitrary JS execution with SSRF capability.
Fix: Disabled by default via CRAWL4AI_EXECUTE_JS_ENABLED env var. Added SSRF blocklist on destination URL. Removed --disable-web-security from default browser args.
6. Hardcoded JWT Secret Key (CWE-798, CVSS 9.8)
The JWT signing key defaults to "mysecret" in the public source code, allowing anyone to forge valid authentication tokens.
Fix: Removed default value. Added startup validation rejecting weak/short secrets. Auto-generates ephemeral key when JWT enabled but no key set.
7. SSRF via Direct Crawl Endpoints /crawl, /md, /llm (CWE-918, CVSS 8.6)
The primary crawl entry points (/crawl, /crawl/stream, /md, /llm) fetch arbitrary user-supplied URLs with no destination validation, enabling Server-Side Request Forgery against internal services, Docker networks, and cloud metadata endpoints (169.254.169.254). A blocklist that only inspects the literal hostname is additionally bypassable via IPv6-mapped IPv4 addresses (e.g. [::ffff:169.254.169.254], [::ffff:10.0.0.1]), which resolve to the blocked private/metadata ranges but evade a naive string check.
Fix: Added URL destination validation on all crawl/md/llm entry points, reusing the SSRF blocklist (RFC 1918, loopback, link-local, cloud-metadata IPs and hostnames). IPv6-mapped IPv4 addresses are normalized to their IPv4 form before the blocklist check, closing the mapping bypass. raw:// URLs are skipped. Validation applies at request entry, not only at fetch time.
Workarounds
- Upgrade to the patched version (recommended)
- Set
CRAWL4AI_API_TOKENto enable authentication - Set a strong
SECRET_KEY(min 32 chars) if using JWT - Restrict network access to the Docker API
Credits
- Jeongbean Jeon - file write, SSRF, monitor auth bypass, stored XSS
- wulonchia - file write via output_path (independent report)
- by111 (August829) - hardcoded JWT, eval in /config/dump, /execute_js, hook sandbox escape
- secsys_codex - SSRF via /md, /crawl, /llm endpoints + IPv6-mapped IPv4 bypass (URL destination validation)
- Velayutham Selvaraj (LinkedIn) - SSRF via missing host validation in validate_url_scheme (independent report)
- IcySun & Yashon - SSRF, arbitrary file write, missing-auth-by-default, hook sandbox bypass via asyncio (independent report)
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | crawl4ai | < 0.8.7 | 0.8.7 |
References
- https://github.com/advisories/GHSA-xrfj-6m49-wfmm
- https://www.vulncheck.com/advisories/crawl4ai-unauthenticated-access-to-monitor-endpoints-via-docker-api-server
- https://github.com/unclecode/crawl4ai
- https://github.com/advisories/GHSA-53rg-46cm-4g2v
- https://www.vulncheck.com/advisories/crawl4ai-stored-cross-site-scripting-in-monitor-dashboard
- https://github.com/advisories/GHSA-8qrg-7j2f-rf2h
- https://www.vulncheck.com/advisories/crawl4ai-authentication-bypass-via-hardcoded-jwt-signing-key
- https://www.vulncheck.com/advisories/crawl4ai-server-side-request-forgery-via-webhook-urls
- https://github.com/advisories/GHSA-f23g-2f38-gg94
- https://www.vulncheck.com/advisories/crawl4ai-arbitrary-file-write-via-output-path-parameter
- https://github.com/advisories/GHSA-r9hw-78q5-478g
- https://github.com/unclecode/crawl4ai/security/advisories/GHSA-365w-hqf6-vxfg
- https://www.vulncheck.com/advisories/crawl4ai-server-side-request-forgery-via-direct-crawl-endpoints
- https://github.com/advisories/GHSA-g2pv-76hm-j4x9
- https://www.vulncheck.com/advisories/crawl4ai-arbitrary-javascript-execution-via-execute-js-endpoint
- https://nvd.nist.gov/vuln/detail/CVE-2026-56265
- https://github.com/unclecode/crawl4ai/releases/tag/v0.8.7
- https://nvd.nist.gov/vuln/detail/CVE-2026-56266
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-798.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-596.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-3449.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-3443.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-239.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-230.yaml
- https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-229.yaml
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-798, CWE-22, CWE-306, CWE-79, CWE-918, CWE-94- Platform
- Python (PyPI)
- Package
crawl4ai- Disclosed
- 16.06.2026
- Updated
- 11.10.2026 15:18
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-229 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-230 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-239 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-596 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-798 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-3443 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - PYSEC-2026-3449 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-8qrg-7j2f-rf2h - CC BY 4.0
OSV / GitHub Advisory Database - GHSA-365w-hqf6-vxfg - CC BY 4.0
Vulnerability history: crawl4ai
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 12
- First → latest
- 04.2025 06.2026
- Without a fix
- 1
- Exploited in attacks
- 0
Severity breakdown
- Critical 6
- High 5
- Medium 1
Disclosures per year
- 2025: 1
- 2026: 11
-
Crawl4AI: Multiple Docker API Vulnerabilities - File Write, SSRF, Auth Bypass, XSS, JS Execution this entry
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