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.
Fix
Public exploits 2
- 0xEnc0der/CVE-2026-53753 PoC on GitHub
- BiiTts/CVE-2026-53753-Crawl4AI-RCE PoC on GitHub
Each line links to the index that lists it, never to exploit code. Exploit-DB's "verified" and a Metasploit rank of good or better count as verified; a PoC-in-GitHub entry is a repository's claim.
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 Third Party Advisory, Mitigation
- https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 Third Party Advisory, Mitigation
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 10.0 · kidocodeNVD modified 2026-10-25 23:10
Affected (CPE criteria) 1
cpe:2.3:a:kidocode:crawl4ai:*:*:*:*:*:*:*:*
References 2
- https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 Third Party Advisory, Mitigation
- https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 Third Party Advisory, Mitigation