CVE-2026-53753

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.

• CWE-94
• CWE-913

• https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7Third Party Advisory, Mitigation
• https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7Third Party Advisory, Mitigation

Published

Jun 23, 2026

Last Modified

Jun 29, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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