CVE-2025-44594 is a critical security vulnerability identified in the halo software, specifically versions 2.20.17 and earlier. The vulnerability is a server-side request forgery (SSRF) flaw located in the API endpoint /apis/uc.api.storage.halo.run/v1alpha1/attachments/-/upload-from-url. SSRF vulnerabilities occur when an attacker can manipulate a server to make unintended requests to internal or external systems, potentially bypassing network access controls. In this case, the vulnerable endpoint allows uploading attachments by fetching content from a URL provided by the user. Due to insufficient validation or sanitization of the URL parameter, an attacker can craft malicious requests that cause the server to initiate arbitrary HTTP requests to internal resources or external systems. The CVSS v3.1 base score of 9.1 indicates a critical severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The impact on confidentiality and integrity is high (C:H/I:H), while availability impact is none (A:N). This means an attacker can potentially access sensitive internal services, exfiltrate data, or manipulate internal systems without authentication or user interaction. The vulnerability is classified under CWE-918 (Server-Side Request Forgery). No public exploits are currently known, and no patches have been linked yet. The vulnerability was reserved in April 2025 and published in September 2025, indicating recent discovery and disclosure. Given the critical nature and ease of exploitation, this SSRF vulnerability poses a significant risk to any organization running affected halo versions, especially if the server has access to sensitive internal networks or cloud metadata services.

For European organizations using halo v2.20.17 or earlier, this vulnerability presents a severe risk. SSRF can be leveraged to access internal services that are otherwise protected by firewalls, such as internal APIs, databases, or cloud provider metadata endpoints (e.g., AWS, Azure, GCP). This can lead to unauthorized data disclosure, credential theft, or lateral movement within the network. Given the critical CVSS score and no requirement for authentication, attackers can exploit this remotely over the internet, increasing the attack surface. Organizations in sectors with sensitive data—such as finance, healthcare, government, and critical infrastructure—are particularly at risk. The ability to compromise confidentiality and integrity without impacting availability means attackers can stealthily exfiltrate data or manipulate internal systems without immediate detection. Additionally, the lack of known public exploits suggests that proactive mitigation is essential before attackers develop or deploy exploit code. The vulnerability could also be used as a foothold for more complex attacks, including ransomware or espionage campaigns targeting European entities.

1. Immediate patching: Organizations should monitor halo vendor advisories closely and apply security patches as soon as they become available. 2. Network segmentation: Restrict the halo server's outbound network access to only trusted external endpoints and block access to internal management interfaces and cloud metadata IP ranges (e.g., 169.254.169.254). 3. Input validation: Implement strict validation and sanitization on URLs accepted by the upload-from-url API to prevent requests to internal IP ranges or unauthorized domains. 4. Web application firewall (WAF): Deploy WAF rules to detect and block SSRF attack patterns targeting the vulnerable endpoint. 5. Monitoring and logging: Enable detailed logging of outbound requests from the halo server and monitor for unusual or unauthorized internal requests. 6. Access controls: Limit exposure of the vulnerable API endpoint to trusted users or networks where possible. 7. Incident response readiness: Prepare to detect and respond to potential SSRF exploitation attempts, including network traffic analysis and endpoint forensics. These measures combined reduce the risk of exploitation while awaiting official patches.