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Public proof of conceptFix available

CVE-2026-53753

A public proof of concept exists; no exploitation attested.

  • Published2026-06-23
  • Fixed in0.8.7
  • WeaknessCWE-913 · CWE-94

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-06-2319:17CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-53753?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-53753?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Kidocode crawl4ai
BranchAffectedFixed in
0.8< 0.8.70.8.7

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Kidocode crawl4ai to 0.8.7

Advisories and patches

Detection

read 2026-10-23 19:25 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedBiiTts/CVE-2026-53753-Crawl4AI-RCE0xEnc0der/CVE-2026-53753
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2026-06-23
  • OpenCVESSVC decisionpoc—
  • CNACVSS 3.19.8read 2026-10-23
  • NVDCVSS 3.110read 2026-10-23
  • CNAweakness (CWE)CWE-913, CWE-94read 2026-10-23
  • FIRST EPSSEPSS score2.9 %2026-10-22
  • PoC-in-GitHubproof of concept2read 2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Published
2026-06-23
Last Modified
2026-06-29
NVD status
Analyzed

Frequently asked questions

What is 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.

Is CVE-2026-53753 actively exploited?

A proof-of-concept exploit exists for CVE-2026-53753, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-53753?

CVE-2026-53753 has a CVSS v3 base score of 10 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

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