CVE-2026-53753
Description
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.
How to fix
- kidocode crawl4ai0.8.7 or later
- crawl4ai0.8.7 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| kidocode crawl4ai | v < 0.8.7 | 0.8.7 |
| crawl4aiPyPI | v < 0.8.7 | 0.8.7 |
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Attack Surface Management
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