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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| unclecode | crawl4ai | < 0.8.7 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 1 repository
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BiiTts/CVE-2026-53753-Crawl4AI-RCE ★ 4 · Jun 29, 2026
CVE-2026-53753 — Crawl4AI <0.8.7 unauthenticated RCE (AST sandbox escape via gi_frame.f_back). Lab + PoC, verified e2e.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Automated scanner template
A ready-made Nuclei template detects this vulnerability automatically. Vulnerabilities with public scanner templates are typically probed across the internet soon after the template appears — exposed systems should be patched first.
- Crawl4AI <= 0.8.6 - Remote Code Execution http/cves/2026/CVE-2026-53753.yaml
Source: projectdiscovery/nuclei-templates (MIT) — updated daily. Only links are listed.
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | crawl4ai | < 0.8.7 | 0.8.7 | GHSA-qxjp-w3pj-48m7 |