Vulnerability Details CVE-2026-53753
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.004
EPSS Ranking 35.9%
CVSS Severity
CVSS v3 Score 9.8
References
Products affected by CVE-2026-53753
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cpe:2.3:a:kidocode:crawl4ai:0.1.0
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cpe:2.3:a:kidocode:crawl4ai:0.2.0
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cpe:2.3:a:kidocode:crawl4ai:0.2.1
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cpe:2.3:a:kidocode:crawl4ai:0.2.2
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cpe:2.3:a:kidocode:crawl4ai:0.2.4
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cpe:2.3:a:kidocode:crawl4ai:0.2.6
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cpe:2.3:a:kidocode:crawl4ai:0.2.7
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cpe:2.3:a:kidocode:crawl4ai:0.2.71
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cpe:2.3:a:kidocode:crawl4ai:0.2.72
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cpe:2.3:a:kidocode:crawl4ai:0.2.73
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cpe:2.3:a:kidocode:crawl4ai:0.2.74
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cpe:2.3:a:kidocode:crawl4ai:0.2.77
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cpe:2.3:a:kidocode:crawl4ai:0.3.0
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cpe:2.3:a:kidocode:crawl4ai:0.3.3
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cpe:2.3:a:kidocode:crawl4ai:0.3.6
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cpe:2.3:a:kidocode:crawl4ai:0.3.745
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cpe:2.3:a:kidocode:crawl4ai:0.3.746
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cpe:2.3:a:kidocode:crawl4ai:0.4.24
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cpe:2.3:a:kidocode:crawl4ai:0.4.243
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cpe:2.3:a:kidocode:crawl4ai:0.4.247
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cpe:2.3:a:kidocode:crawl4ai:0.5.0
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cpe:2.3:a:kidocode:crawl4ai:0.6.0
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cpe:2.3:a:kidocode:crawl4ai:0.6.3
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cpe:2.3:a:kidocode:crawl4ai:0.7.0
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cpe:2.3:a:kidocode:crawl4ai:0.7.1
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cpe:2.3:a:kidocode:crawl4ai:0.7.2
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cpe:2.3:a:kidocode:crawl4ai:0.7.3
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cpe:2.3:a:kidocode:crawl4ai:0.7.4
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cpe:2.3:a:kidocode:crawl4ai:0.7.5
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cpe:2.3:a:kidocode:crawl4ai:0.7.6
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cpe:2.3:a:kidocode:crawl4ai:0.7.7
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cpe:2.3:a:kidocode:crawl4ai:0.7.8
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cpe:2.3:a:kidocode:crawl4ai:0.8.0
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cpe:2.3:a:kidocode:crawl4ai:0.8.5
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cpe:2.3:a:kidocode:crawl4ai:0.8.6