CVE-2026-53753 – Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain – Pre-Auth RCE in Docker API

CVE ID :CVE-2026-53753

Published : June 23, 2026, 6:17 p.m. | 1 hour, 26 minutes ago

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.

Severity: 0.0 | NA

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