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CVE-2026-53753

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

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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 · EPSS 2.9% · Public exploit · Fix available

Published
Updated

Stack: python

Affected products and versions

  • crawl4ai

    Versions
    • < 0.8.7: Affected

    No fix published

  • crawl4ai PyPI

    Versions
    • 0.3.0
    • 0.3.1
    • 0.3.2
    • 0.3.3
    • 0.3.4
    • 0.3.5
    • 0.3.6
    • 0.3.7
    • 0.3.71
    • 0.3.72
    • 0.3.73
    • 0.3.731
    • 0.3.74
    • 0.3.741
    • 0.3.742
    • 0.3.743
    • 0.3.744
    • 0.3.745
    • 0.3.746
    • 0.3.8
    • 0.4.0
    • 0.4.1
    • 0.4.21
    • 0.4.22
    • 0.4.23
    • 0.4.24
    • 0.4.241
    • 0.4.242
    • 0.4.243
    • 0.4.244
    • 0.4.245
    • 0.4.246
    • 0.4.247
    • 0.4.248
    • 0.4.248b3
    • 0.4.3b1
    • 0.4.3b2
    • 0.4.3b3
    • 0.5.0
    • 0.5.0.post1
    • 0.5.0.post2
    • 0.5.0.post3
    • 0.5.0.post4
    • 0.5.0.post5
    • 0.5.0.post6
    • 0.5.0.post7
    • 0.5.0.post8
    • 0.6.0
    • 0.6.0rc1
    • 0.6.1
    • 0.6.2
    • 0.6.3
    • 0.7.0
    • 0.7.1
    • 0.7.2
    • 0.7.3
    • 0.7.4
    • 0.7.5
    • 0.7.6
    • 0.7.7
    • 0.7.8
    • 0.8.0
    • 0.8.5
    • 0.8.6
    Affected ranges
    • ECOSYSTEM: < 0.8.7

    Update to 0.8.7

Original sources

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