CVE-2026-53753
Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API
CVSS Score
9.8
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-94 CWE-913 |
| Vendor | unclecode |
| Product | crawl4ai |
| Published | Jun 23, 2026 |
| Last Updated | Jun 23, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Affected Versions
unclecode / crawl4ai
< 0.8.7