CVE-2026-53753: Kidocode CRAWL4AI

Critical severity, CVSS 10.0. EPSS: 2.9% chance of exploitation in the next 30 days.

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.

Affected products

• Kidocode CRAWL4AI: before 0.8.7 (fixed in 0.8.7)

Published 2026-06-23. Last modified 2026-06-29.