trueleaf ApiFlow URL Validation http_proxy.service.ts validateUrlSecurity server-side request forgery

The SSRF vulnerability in ApiFlow allows attackers to craft malicious requests that appear to originate from the ApiFlow server itself. This can be exploited to access internal services and resources that are not directly exposed to the internet. For example, an attacker could potentially access internal databases, configuration files, or other sensitive data. Furthermore, the attacker could leverage the vulnerability to scan the internal network for other vulnerable systems, facilitating lateral movement and expanding the attack surface. The ability to initiate requests on behalf of the server grants a significant degree of control and poses a substantial risk to the confidentiality and integrity of the affected environment.

Organizations deploying ApiFlow 0.9.7, particularly those with sensitive internal resources accessible via the proxy, are at significant risk. Shared hosting environments utilizing ApiFlow are also vulnerable, as a compromised tenant could potentially exploit the SSRF vulnerability to access resources belonging to other tenants.

• nodejs / server:

  journalctl -u apiflow | grep -i "url validation"

• generic web:

  curl -I <apiFlow_server_url>/<potentially_malicious_url>
  # Check for unexpected internal IP addresses or hostnames in the response headers

1. 2026-03-21Disclosure

   disclosure

1. Reserviert2026-03-21
2. Veröffentlicht2026-03-21
3. Geändert2026-03-23
4. EPSS aktualisiert2026-03-29

The primary mitigation for CVE-2026-4528 is to upgrade ApiFlow to a patched version as soon as it becomes available. Until a patch is released, consider implementing temporary workarounds to reduce the attack surface. These may include restricting outbound network access from the ApiFlow server to only necessary destinations, implementing strict URL validation and sanitization on the server-side, and utilizing a Web Application Firewall (WAF) to filter malicious requests. Regularly monitor logs for suspicious activity and implement intrusion detection systems to identify and respond to potential attacks. After upgrade, confirm functionality by testing URL validation and proxy behavior.