{"id":"CVE-2026-53753","summary":"Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API","details":"Crawl4AI is an open-source LLM friendly web crawler & 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.","aliases":["GHSA-qxjp-w3pj-48m7","PYSEC-2026-319"],"modified":"2026-07-08T08:12:35.268971550Z","published":"2026-06-23T18:17:18.936Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53753.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-913","CWE-94"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53753.json"},{"type":"ADVISORY","url":"https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53753"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/unclecode/crawl4ai","events":[{"introduced":"0"},{"fixed":"7b280d36b150b544bf0994285b4755dca18c2149"}],"database_specific":{"cpe":"cpe:2.3:a:kidocode:crawl4ai:*:*:*:*:*:*:*:*","source":["AFFECTED_FIELD","CPE_RANGE"],"extracted_events":[{"introduced":"0"},{"fixed":"0.8.7"}]}}],"versions":["docker-rebuild-v0.8.6","v0.8.6","v0.7.4","v0.7.3","v0.7.2","v0.7.1","v0.7.0","vr0.6.3","v0.6.3","vr0.6.0","vr0.6.0rc1","v0.5.0.post1","v0.4.243","v0.4.24","v0.3.745","v.3.72","v0.3.6","0.3.4","v0.3.3","v0.3.0","v0.2.77","v0.0.75","v0.2.74","v0.2.73","v0.2.72","v0.2.71","v0.2.7","v0.2.6","v0.2.4","v0.2.1","v0.2.0","v0.1.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53753.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}