CVE-2026-53753 Details
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.
A remote code execution vulnerability has been identified in Crawl4AI versions prior to 0.8.7. The issue arises in the computed fields feature, where the '_safe_eval_expression()' function uses an Abstract Syntax Tree (AST) validator that only blocks attributes starting with an underscore. This oversight allows access to Python generator and frame object attributes, such as 'gi_frame', 'f_back', and 'f_builtins', which do not start with an underscore. Exploitation of this vulnerability enables a complete sandbox escape, allowing arbitrary code execution. The attack can be executed without authentication, as JSON Web Token (JWT) verification is disabled by default. The vulnerability is triggered by sending a POST request to '/crawl' with a crafted extraction schema.
Upgrade to Crawl4AI version 0.8.7 or later. If an immediate upgrade is not possible, enable JWT authentication by setting the 'CRAWL4AI_API_TOKEN' environment variable and restrict network access to the Docker API.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jun 23, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 | CISA-ADP | Third Party AdvisoryMitigation |
| https://github.com/unclecode/crawl4ai/security/advisories/GHSA-qxjp-w3pj-48m7 | [email protected] | Third Party AdvisoryMitigation |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-913 | Improper Control of Dynamically-Managed Code Resources | [email protected] |
| CWE-94 | Improper Control of Generation of Code ('Code Injection') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| kidocode crawl4ai | < 0.8.7 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 29, 2026 | Initial Analysis | [email protected] |
| Jun 23, 2026 | CVE Modified | CISA-ADP |
| Jun 23, 2026 | New CVE Received | [email protected] |