🛡️ CVE-2026-56258 — crawl4ai

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-117 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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

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.

1. Arbitrary file write via output_path symlink / TOCTOU (primary)

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).

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2026-56258 is recorded against 1 package.

  • crawl4ai (fixed in 0.8.8)

Timeline and source

Published on 16 June 2026 and last revised on 21 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Package)
www.vulncheck.com (Web)

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-117
Public Exploit ✅ No
Source OSV
Published 2026-06-16
Updated 2026-08-12
Modified 2026-07-21
Fix URL N/A

Affected Packages

Software From version Fixed in
crawl4ai — 0.8.8

Similar Threats

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