{"id":"CVE-2026-53753","aliases":["EUVD-2026-38569","GHSA-qxjp-w3pj-48m7","PYSEC-2026-319"],"status":"published","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"Crawl4AI is an open-source LLM friendly web crawler \u0026 scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.029,"percentile":0.87062,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-913","CWE-94"],"published":"2026-06-16T20:13:07Z","modified":"2026-10-28T02:30:54Z","exploits":[{"source":"nuclei","id":"CVE-2026-53753","title":"Crawl4AI \u003c= 0.8.6 - Remote Code Execution","type":"detection template","url":"https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-53753.yaml"},{"source":"pocgithub","id":"0xEnc0der/CVE-2026-53753","title":"0xEnc0der/CVE-2026-53753","date":"2026-07-02","url":"https://github.com/0xEnc0der/CVE-2026-53753"},{"source":"pocgithub","id":"BiiTts/CVE-2026-53753-Crawl4AI-RCE","title":"BiiTts/CVE-2026-53753-Crawl4AI-RCE","date":"2026-06-29","url":"https://github.com/BiiTts/CVE-2026-53753-Crawl4AI-RCE"}],"fixes":[{"ecosystem":"PyPI","package":"crawl4ai","fixed_in":["0.8.7"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"crawl4ai","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"0.8.6"},{"fixed":"0.8.7"}]}]},{"source":"osv","ecosystem":"PyPI","package":"crawl4ai","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.8.7"}]}],"versions":["0.3.0","0.3.1","0.3.2","0.3.3","0.3.4","0.3.5","0.3.6","0.3.7","0.3.71","0.3.72","0.3.73","0.3.731","0.3.74","0.3.741","0.3.742","0.3.743","0.3.744","0.3.745","0.3.746","0.3.8","0.4.0","0.4.1","0.4.21","0.4.22","0.4.23","0.4.24","0.4.241","0.4.242","0.4.243","0.4.244","0.4.245","0.4.246","0.4.247","0.4.248","0.4.248b3","0.4.3b1","0.4.3b2","0.4.3b3","0.5.0","0.5.0.post1","0.5.0.post2","0.5.0.post3","0.5.0.post4","0.5.0.post5","0.5.0.post6","0.5.0.post7","0.5.0.post8","0.6.0","0.6.0rc1","0.6.1","0.6.2","0.6.3","0.7.0","0.7.1","0.7.2","0.7.3","0.7.4","0.7.5","0.7.6","0.7.7","0.7.8","0.8.0","0.8.5","0.8.6"]},{"source":"osv","ecosystem":"PyPI","package":"crawl4ai","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.8.7"}]}],"versions":["0.3.0","0.3.1","0.3.2","0.3.3","0.3.4","0.3.5","0.3.6","0.3.7","0.3.71","0.3.72","0.3.73","0.3.731","0.3.74","0.3.741","0.3.742","0.3.743","0.3.744","0.3.745","0.3.746","0.3.8","0.4.0","0.4.1","0.4.21","0.4.22","0.4.23","0.4.24","0.4.241","0.4.242","0.4.243","0.4.244","0.4.245","0.4.246","0.4.247","0.4.248","0.4.248b3","0.4.3b1","0.4.3b2","0.4.3b3","0.5.0","0.5.0.post1","0.5.0.post2","0.5.0.post3","0.5.0.post4","0.5.0.post5","0.5.0.post6","0.5.0.post7","0.5.0.post8","0.6.0","0.6.0rc1","0.6.1","0.6.2","0.6.3","0.7.0","0.7.1","0.7.2","0.7.3","0.7.4","0.7.5","0.7.6","0.7.7","0.7.8","0.8.0","0.8.5","0.8.6"]}],"products":[{"vendor":"kidocode","product":"crawl4ai"},{"vendor":"unclecode","product":"crawl4ai"}],"references":[{"url":"https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7","tags":["x_refsource_CONFIRM","exploit","Third Party Advisory","Mitigation","advisory","web"]},{"url":"https://github.com/unclecode/crawl4ai/pull/1855","tags":["web"]},{"url":"https://github.com/unclecode/crawl4ai/pull/1886","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53753","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-qxjp-w3pj-48m7","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/crawl4ai/PYSEC-2026-319.yaml","tags":["web"]},{"url":"https://github.com/unclecode/crawl4ai","tags":["package"]},{"url":"https://pypi.org/project/crawl4ai","tags":["web","package"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53753.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-53753","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"Crawl4AI is an open-source LLM friendly web crawler \u0026 scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.","status":"published","published":"2026-06-23T18:17:18.936Z","modified":"2026-06-23T18:55:22.278Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-94","CWE-913"],"updated_at":"2026-11-02T14:19:59.761005Z"}],"euvd":[{"id":"EUVD-2026-38569","description":"Crawl4AI is an open-source LLM friendly web crawler \u0026 scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.","status":"published","published":"2026-06-23T18:17:18Z","modified":"2026-06-23T18:55:22Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T18:20:31.51905Z"}],"ghsa":[{"id":"GHSA-qxjp-w3pj-48m7","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"### Summary\n\nThe `_safe_eval_expression()` function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (`gi_frame`, `f_back`, `f_builtins`) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution.\n\nThe attack requires no authentication (JWT disabled by default) and is triggered via `POST /crawl` with a crafted extraction schema.\n\n### Attack Vector\n\nAn attacker sends a `POST /crawl` request with a `JsonCssExtractionStrategy` schema containing a malicious computed field expression that:\n1. Creates a generator to access `gi_frame`\n2. Walks the frame chain via `f_back`\n3. Reaches `f_builtins` containing the real `__import__`\n4. Imports `os` and executes arbitrary commands\n\n### Impact\n\nUnauthenticated remote code execution inside the Docker container. An attacker can execute arbitrary system commands, read/write files, and exfiltrate secrets.\n\n### Fix Details\n\n1. Removed `eval()` from computed field expression path entirely -- expressions now log a warning and return default value\n2. Deleted `_safe_eval_expression()` function and `_SAFE_EVAL_BUILTINS` (dead security-sensitive code)\n3. `function` key with Python callables still works for SDK users\n4. Replaced `eval()` in `/config/dump` with JSON-based input validated by Pydantic\n5. Fixed hook_manager sandbox: stripped `__builtins__`, `__loader__`, `__spec__` from injected modules; removed `getattr`, `setattr`, `type`, `__build_class__` from allowed builtins\n\n### Workarounds\n\n1. Upgrade to the patched version (recommended)\n2. Enable JWT authentication via `CRAWL4AI_API_TOKEN` environment variable\n3. Restrict network access to the Docker API\n\n### Credits\n\n- Song Binglin ([q1uf3ng](https://github.com/q1uf3ng)) - reported the AST sandbox escape\n- by111 ([August829](https://github.com/August829)) - reported the hook sandbox `__builtins__` escape and hardcoded JWT secret bypass\n- [jannahopp](https://github.com/jannahopp) - PR #1855 proposing eval removal\n- [ntohidi](https://github.com/ntohidi) - PR #1886 proposing allowlist approach","status":"published","published":"2026-06-16T20:13:07Z","modified":"2026-07-20T21:11:45Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-94","CWE-913"],"updated_at":"2026-11-02T14:40:47.245721Z"}],"nvd":[{"id":"CVE-2026-53753","description":"Crawl4AI is an open-source LLM friendly web crawler \u0026 scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.","status":"published","published":"2026-06-23T19:17:07.107Z","modified":"2026-10-25T23:10:00.167Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"},{"version":"3.1","score":10,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H","level":"critical","assessor":"primary"}],"cwes":["CWE-94","CWE-913"],"updated_at":"2026-11-02T14:12:25.288279Z"}],"osv":[{"id":"CVE-2026-53753","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"Crawl4AI is an open-source LLM friendly web crawler \u0026 scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.","status":"published","published":"2026-06-23T18:17:18.936Z","modified":"2026-10-28T02:30:54.067637262Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-913","CWE-94"],"updated_at":"2026-11-02T15:45:08.132336Z"},{"id":"GHSA-qxjp-w3pj-48m7","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"### Summary\n\nThe `_safe_eval_expression()` function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (`gi_frame`, `f_back`, `f_builtins`) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution.\n\nThe attack requires no authentication (JWT disabled by default) and is triggered via `POST /crawl` with a crafted extraction schema.\n\n### Attack Vector\n\nAn attacker sends a `POST /crawl` request with a `JsonCssExtractionStrategy` schema containing a malicious computed field expression that:\n1. Creates a generator to access `gi_frame`\n2. Walks the frame chain via `f_back`\n3. Reaches `f_builtins` containing the real `__import__`\n4. Imports `os` and executes arbitrary commands\n\n### Impact\n\nUnauthenticated remote code execution inside the Docker container. An attacker can execute arbitrary system commands, read/write files, and exfiltrate secrets.\n\n### Fix Details\n\n1. Removed `eval()` from computed field expression path entirely -- expressions now log a warning and return default value\n2. Deleted `_safe_eval_expression()` function and `_SAFE_EVAL_BUILTINS` (dead security-sensitive code)\n3. `function` key with Python callables still works for SDK users\n4. Replaced `eval()` in `/config/dump` with JSON-based input validated by Pydantic\n5. Fixed hook_manager sandbox: stripped `__builtins__`, `__loader__`, `__spec__` from injected modules; removed `getattr`, `setattr`, `type`, `__build_class__` from allowed builtins\n\n### Workarounds\n\n1. Upgrade to the patched version (recommended)\n2. Enable JWT authentication via `CRAWL4AI_API_TOKEN` environment variable\n3. Restrict network access to the Docker API\n\n### Credits\n\n- Song Binglin ([q1uf3ng](https://github.com/q1uf3ng)) - reported the AST sandbox escape\n- by111 ([August829](https://github.com/August829)) - reported the hook sandbox `__builtins__` escape and hardcoded JWT secret bypass\n- [jannahopp](https://github.com/jannahopp) - PR #1855 proposing eval removal\n- [ntohidi](https://github.com/ntohidi) - PR #1886 proposing allowlist approach","status":"published","published":"2026-06-16T20:13:07Z","modified":"2026-07-20T21:30:41.637534684Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-913","CWE-94"],"updated_at":"2026-11-02T15:46:55.122811Z"},{"id":"PYSEC-2026-319","title":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","description":"### Summary\n\nThe `_safe_eval_expression()` function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (`gi_frame`, `f_back`, `f_builtins`) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution.\n\nThe attack requires no authentication (JWT disabled by default) and is triggered via `POST /crawl` with a crafted extraction schema.\n\n### Attack Vector\n\nAn attacker sends a `POST /crawl` request with a `JsonCssExtractionStrategy` schema containing a malicious computed field expression that:\n1. Creates a generator to access `gi_frame`\n2. Walks the frame chain via `f_back`\n3. Reaches `f_builtins` containing the real `__import__`\n4. Imports `os` and executes arbitrary commands\n \n### Impact\n\nUnauthenticated remote code execution inside the Docker container. An attacker can execute arbitrary system commands, read/write files, and exfiltrate secrets.\n\n### Fix Details\n\n1. Removed `eval()` from computed field expression path entirely -- expressions now log a warning and return default value\n2. Deleted `_safe_eval_expression()` function and `_SAFE_EVAL_BUILTINS` (dead security-sensitive code)\n3. `function` key with Python callables still works for SDK users\n4. Replaced `eval()` in `/config/dump` with JSON-based input validated by Pydantic\n5. Fixed hook_manager sandbox: stripped `__builtins__`, `__loader__`, `__spec__` from injected modules; removed `getattr`, `setattr`, `type`, `__build_class__` from allowed builtins\n \n### Workarounds\n\n1. Upgrade to the patched version (recommended)\n2. Enable JWT authentication via `CRAWL4AI_API_TOKEN` environment variable\n3. Restrict network access to the Docker API\n\n### Credits\n\n- Song Binglin ([q1uf3ng](https://github.com/q1uf3ng)) - reported the AST sandbox escape\n- by111 ([August829](https://github.com/August829)) - reported the hook sandbox `__builtins__` escape and hardcoded JWT secret bypass\n - [jannahopp](https://github.com/jannahopp) - PR #1855 proposing eval removal\n - [ntohidi](https://github.com/ntohidi) - PR #1886 proposing allowlist approach","status":"published","published":"2026-06-29T11:50:52.380343Z","modified":"2026-07-13T16:15:23.309571287Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:52:56.429374Z"}]}}