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Critical 9.8Published Jun 23, 2026

CVE-2026-53753Crawl4AI: AST Sandbox Escape via gi_frame.f_back Chain - Pre-Auth RCE in Docker API

Updated under an hour ago ()

Does this affect you?

It affects unclecode crawl4ai and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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.

CVSS
9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE)
CWE-94, CWE-913
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
GitHub_M
NVD analysis
Analyzed
Record last updated
Jun 23, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
unclecode crawl4ai
unclecode:crawl4ai (from the name)
before 0.8.7
CNA record
kidocode crawl4ai
kidocode:crawl4ai
before 0.8.7
NVD

References

References

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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