CVE-2026-53753 | THREATINT

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.

PUBLISHED Reserved 2026-06-10 | Published 2026-06-23 | Updated 2026-06-23 | Assigner GitHub_M

CRITICAL: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-94: Improper Control of Generation of Code ('Code Injection')

CWE-913: Improper Control of Dynamically-Managed Code Resources

Product status

< 0.8.7

affected

References

github.com/...awl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 exploit

github.com/...awl4ai/security/advisories/GHSA-qxjp-w3pj-48m7

cve.org (CVE-2026-53753)

nvd.nist.gov (CVE-2026-53753)

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