Vulnerability Database

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Total vulnerabilities in the database

Crawl4AI: Arbitrary file write (symlink/TOCTOU) plus log and webhook-header injection in Docker server — Crawl4AI

Improper Output Neutralization for Logs

Summary

Three backward-compatible hardening fixes in the Docker API server. The headline issue is an arbitrary file write via the screenshot/PDF output_path.

POST /screenshot and POST /pdf accept an output_path constrained to ALLOWED_OUTPUT_DIR by validate_output_path. The 0.8.7 check was string-only: it did not resolve symlinks, so a symlinked path component inside the output directory could redirect the write outside the directory, and the final open() followed symlinks. On a deployment where the runtime user can write executable/cron locations this is an arbitrary-write to code-execution primitive. The API is unauthenticated by default.

Fix: validate_output_path now resolves the real path (symlinks) of the parent and re-checks containment, and the write uses O_NOFOLLOW (write_output_file). output_path remains supported.

2. CRLF log injection (CWE-117)

User-controlled URLs/errors reflected into log lines could embed CR/LF and forge additional log entries. Fix: a logging filter strips CR/LF/control characters from all records.

3. Webhook request-header injection (CWE-93/CWE-113)

User-supplied webhook headers were sent verbatim, allowing CRLF and hop-by-hop / sensitive header injection on the outbound webhook request. Fix: webhook headers are validated (name pattern, no control characters, deny Host/Content-Length/Transfer-Encoding/Authorization/Cookie/...), with early request-time rejection.

Impact

Arbitrary file write (potential code execution) for #1; log forging for #2; request smuggling / header injection on outbound webhooks for #3.

Workarounds

  • Upgrade to the patched version.
  • Enable authentication (CRAWL4AI_API_TOKEN).
  • Run the container with a read-only root filesystem.

Credits

Internal security audit (Crawl4AI maintainers).

  • Published: Jun 16, 2026
  • Updated: Jun 17, 2026
  • GHSA: GHSA-7cx2-g3h9-382p
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: High
  • Score: 8.1
  • AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

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