GHSA-365W-HQF6-VXFG
Vulnerability from github – Published: 2026-06-16 20:13 – Updated: 2026-06-24 13:05Summary
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": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.8.6"
},
"package": {
"ecosystem": "PyPI",
"name": "crawl4ai"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.8.7"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-56266"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-306",
"CWE-79",
"CWE-798",
"CWE-918",
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-16T20:13:30Z",
"nvd_published_at": "2026-06-22T22:16:50Z",
"severity": "CRITICAL"
},
"details": "### Summary\n\nMultiple security vulnerabilities in the Crawl4AI Docker API server affecting endpoints for crawling, markdown/LLM extraction, screenshots, PDFs, webhooks, monitoring, JavaScript execution, and configuration.\n\n### Vulnerabilities\n\n#### 1. Arbitrary File Write via /screenshot and /pdf (CWE-22, CVSS 9.1)\n\nThe `output_path` parameter accepts arbitrary filesystem paths with no validation. An attacker can overwrite server files (DoS) or write to any appuser-writable location.\n\n**Fix:** Added `validate_output_path()` restricting writes to `CRAWL4AI_OUTPUT_DIR` (/tmp/crawl4ai-outputs by default). Added Pydantic `field_validator` rejecting `..` traversal sequences.\n\n#### 2. SSRF via Webhook URL (CWE-918, CVSS 8.6)\n\nWebhook 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.\n\n**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`.\n\n#### 3. Authentication Bypass on Monitor Endpoints (CWE-306, CVSS 6.5)\n\nThe monitor router was mounted without `token_dep` dependency, making all monitoring endpoints (including destructive ones like `/monitor/actions/cleanup`) accessible without authentication.\n\n**Fix:** Added `dependencies=[Depends(token_dep)]` to monitor router. Added explicit token check on WebSocket `/monitor/ws` endpoint.\n\n#### 4. Stored XSS in Monitor Dashboard (CWE-79, CVSS 6.1)\n\nURLs and error messages rendered in the monitor dashboard via `innerHTML` without escaping, enabling stored XSS via crafted crawl URLs.\n\n**Fix:** Server-side `html.escape()` on URL and error storage. Client-side `escapeHtml()` wrapper on all `innerHTML` template injections.\n\n#### 5. Arbitrary JavaScript Execution via /execute_js (CWE-94, CVSS 8.1)\n\nThe `/execute_js` endpoint accepts and executes arbitrary JavaScript in the server\u0027s browser with `--disable-web-security` enabled, combining arbitrary JS execution with SSRF capability.\n\n**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.\n\n#### 6. Hardcoded JWT Secret Key (CWE-798, CVSS 9.8)\n\nThe JWT signing key defaults to `\"mysecret\"` in the public source code, allowing anyone to forge valid authentication tokens.\n\n**Fix:** Removed default value. Added startup validation rejecting weak/short secrets. Auto-generates ephemeral key when JWT enabled but no key set.\n\n#### 7. SSRF via Direct Crawl Endpoints /crawl, /md, /llm (CWE-918, CVSS 8.6)\n\nThe 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.\n\n**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.\n\n### Workarounds\n\n1. Upgrade to the patched version (recommended)\n2. Set `CRAWL4AI_API_TOKEN` to enable authentication\n3. Set a strong `SECRET_KEY` (min 32 chars) if using JWT\n4. Restrict network access to the Docker API\n\n### Credits\n\n- Jeongbean Jeon - file write, SSRF, monitor auth bypass, stored XSS\n- wulonchia - file write via output_path (independent report)\n- by111 ([August829](https://github.com/August829)) - hardcoded JWT, eval in /config/dump, /execute_js, hook sandbox escape\n- secsys_codex - SSRF via /md, /crawl, /llm endpoints + IPv6-mapped IPv4 bypass (URL destination validation)\n- Velayutham Selvaraj ([LinkedIn](https://www.linkedin.com/in/velayuthamselvaraj)) - SSRF via missing host validation in validate_url_scheme (independent report)\n- IcySun \u0026 Yashon - SSRF, arbitrary file write, missing-auth-by-default, hook sandbox bypass via asyncio (independent report)",
"id": "GHSA-365w-hqf6-vxfg",
"modified": "2026-06-24T13:05:44Z",
"published": "2026-06-16T20:13:30Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/unclecode/crawl4ai/security/advisories/GHSA-365w-hqf6-vxfg"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-56266"
},
{
"type": "PACKAGE",
"url": "https://github.com/unclecode/crawl4ai"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/crawl4ai-server-side-request-forgery-via-direct-crawl-endpoints"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
],
"summary": "Crawl4AI: Multiple Docker API Vulnerabilities - File Write, SSRF, Auth Bypass, XSS, JS Execution"
}
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.