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Crawl4AI Server-Side Request Forgery Vulnerability (CVE-2026-56261)

Crawl4AI versions before 0.8.7 contain a server-side request forgery (SSRF) vulnerability, CVE-2026-56261, in its Docker API server's webhook endpoints, allowing an attacker to coerce the server into making requests to internal services and potentially expose cloud metadata.

A critical server-side request forgery (SSRF) vulnerability, identified as CVE-2026-56261, exists in Crawl4AI software versions prior to 0.8.7. This flaw is present in the Docker API server's /crawl/job and /llm/job endpoints, which accept webhook URLs without adequate destination validation. An attacker can exploit this by supplying specially crafted webhook URLs that direct the vulnerable server to make requests to internal IP ranges, Docker networks, or cloud metadata endpoints, such as 169.254.169.254. This unchecked redirection can lead to the exposure of sensitive internal network information and cloud metadata, posing a significant risk for unauthorized access, data exfiltration, and further compromise of cloud infrastructure. Organizations running affected versions are urged to patch immediately.

Attack Chain

  1. Vulnerability Identification: An attacker identifies a publicly accessible Crawl4AI instance running a version prior to 0.8.7.
  2. Endpoint Targeting: The attacker targets the Docker API server's vulnerable endpoints, specifically /crawl/job or /llm/job, which process webhook URLs.
  3. Malicious Webhook Crafting: The attacker crafts a malicious HTTP POST request to one of these endpoints, embedding a webhook URL parameter. This parameter contains an internal IP address (e.g., http://192.168.1.1/internal_service), a Docker network address, or a cloud metadata endpoint (e.g., http://169.254.169.254/latest/meta-data/).
  4. Server-Side Request Initiation: Without proper validation, the Crawl4AI server processes the attacker's request and initiates an outbound HTTP request to the internal/metadata URL specified in the malicious webhook.
  5. Information Disclosure: The Crawl4AI server receives the response from the internal service or cloud metadata endpoint, which may contain sensitive data (e.g., internal network configurations, cloud credentials, instance details).
  6. Data Exfiltration/Reconnaissance: The attacker receives the response content from the Crawl4AI server, thereby gaining unauthorized access to internal network information or cloud metadata, facilitating further reconnaissance and potential lateral movement or privilege escalation.

Impact

Successful exploitation of CVE-2026-56261 allows attackers to perform internal network reconnaissance, mapping an organization's network topology and discovering sensitive services not intended for external access. The most significant impact is the potential exposure of cloud metadata, which can include temporary credentials for IAM roles, API keys, and other sensitive configuration details. This exposure can grant attackers unauthorized access to cloud resources, leading to data breaches, resource manipulation, and complete compromise of cloud environments. Organizations running vulnerable Crawl4AI instances face a high risk of severe security incidents and compliance violations.

Recommendation

  • Patching: Immediately upgrade Crawl4AI to version 0.8.7 or later to address CVE-2026-56261 and implement proper webhook URL validation.
  • Network Segmentation: Implement network segmentation and firewall rules to restrict outbound connections from Crawl4AI servers to internal IP ranges and cloud metadata endpoints, except where explicitly required.
  • Monitor Outbound Connections: Monitor network logs for unusual outbound connections initiated by the Crawl4AI server process to internal IP addresses (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) or cloud metadata endpoints like 169.254.169.254.