Summary
CVE-2026-56265 is a critical authentication bypass vulnerability (CWE-798: Use of Hard-coded Credentials) in the Crawl4AI Docker API server, affecting all versions prior to 0.8.7. The flaw stems from a hardcoded default JWT signing key — publicly visible in the project’s source code — that allows any attacker who knows the key to forge valid authentication tokens for any user and gain full access to all protected API functionality. It carries a CVSS 4.0 score of 9.3 and a CVSS 3.1 score of 9.8, both rated Critical.
Technical details
- Root cause: The Crawl4AI Docker API server shipped with a hardcoded default JWT signing key embedded in its publicly available source code (CWE-798). Because the signing secret is static and known, the JWT tokens it produces carry no meaningful cryptographic protection.
- Trigger conditions: Any deployment of the Crawl4AI Docker API server on a version prior to 0.8.7, where JWT authentication is enabled but the default key has not been explicitly replaced by the operator, is fully exposed. No special configuration, account, or elevated privileges are required by the attacker.
- Attack vector: A remote, unauthenticated attacker can use the known default key to construct a cryptographically valid JWT token, present it to the API server, and authenticate as any user without supplying real credentials.
- Impact: Successful exploitation yields full access to all protected API endpoints. High confidentiality, integrity, and availability impact is confirmed by the CVSS vector. The Crawl4AI Docker API exposes capabilities including arbitrary JavaScript execution, file operations, and web crawling hooks — making authentication bypass a gateway to further exploitation of the host.
Affected software
- Crawl4AI (PyPI package) — all versions from 0.0.0 up to and not including 0.8.7
Severity
- CVSS 4.0: 9.3 (Critical) —
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N - CVSS 3.1: 9.8 (Critical) —
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Mitigation and recommended actions
- Immediate: Upgrade to Crawl4AI version 0.8.7 or later. The 0.8.7 release removes the hardcoded default key entirely, adds startup validation that rejects secrets below a minimum length and strength threshold, and automatically generates a secure ephemeral key when JWT authentication is enabled without an explicit secret configured by the operator.
- If immediate patching is not possible: Restrict network-level access to the Docker API server (default port 11235) to trusted internal hosts only. Do not expose the API directly to the public internet. Treat any tokens previously issued under the default key as compromised and rotate them.
IONIX Status
The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.