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Fencer Vulns
critical 9.6

CVE-2026-57571 json

Crawl4AI arbitrary file write via download filename path traversal

published 2026-06-18 4 mo ago modified 2026-10-25 14 d ago also GHSA-2jq4-q6vv-4cp3 , PYSEC-2026-2138 , EUVD-2026-41934

cvss
9.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

Crawl4AI is an open-source LLM-friendly web crawler and scraper. Prior to 0.9.0, when the crawler saves a downloaded file, the destination filename was taken from attacker-influenced input and joined to the downloads directory with no confinement. A filename containing an absolute path or traversal escaped the downloads directory, giving an arbitrary file write with attacker-controlled contents; the HTTP crawler path uses the response Content-Disposition filename and the browser crawler path uses the download's suggested filename. Because the written bytes are attacker-controlled, this can escalate to remote code execution. This issue is fixed in version 0.9.0.

Patch / fix

  • pypi crawl4ai 0.9.0
  • kidocode crawl4ai 0.9.0

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/unclecode/crawl4ai/security/advisories/GHSA-2jq4-q6vv-4cp3 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
OSV 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
GitHub 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
pypi crawl4ai
<0.9.0
0.9.0

Affected products

  • unclecode crawl4ai

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.