by Kastro
Paper/Archive/CVE-2026-53753

CVE-2026-53753

unclecode crawl4ai — Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API

EPSS 3%public exploitCVSS 10.0
critical.is priorityof 100
57
CVSS 10.0 (NVD)10.0 / 10 × 3030.0Not in CISA KEV+300.0EPSS percentile 86.9.869 × 2017.4Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
crawl4ai< 0.8.7–CNA

Scores by source

NVD10.0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
GitHub_M (CNA)9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitgithub.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7