CVE-2026-0600 is a Server-Side Request Forgery (SSRF) vulnerability classified under CWE-918 that affects Sonatype Nexus Repository versions 3.0.0 and later. The vulnerability allows authenticated administrators to configure proxy repositories with URLs that can be manipulated to access unintended network destinations. This includes internal network resources and cloud metadata services, which are typically protected from external access. SSRF vulnerabilities exploit the trust relationship between the vulnerable server and internal or cloud services, enabling attackers to pivot into restricted environments. In this case, the attacker must have administrator privileges within Nexus Repository, which limits the attack surface but still poses a significant risk if credentials are compromised or insiders act maliciously. The vulnerability is present by default, but starting with version 3.88.0, a workaround configuration is available to restrict or validate proxy repository URLs to prevent SSRF exploitation. The vulnerability has a CVSS 4.0 base score of 6.2, reflecting medium severity due to network attack vector, low attack complexity, no user interaction, and the requirement for high privileges. No public exploits have been reported yet, but the potential for internal network reconnaissance and data exfiltration exists. The vulnerability affects a critical component in software supply chains, as Nexus Repository is widely used for artifact storage and distribution, making it an attractive target for attackers aiming to compromise development pipelines or gain lateral movement within corporate networks.

For European organizations, the SSRF vulnerability in Nexus Repository could lead to unauthorized access to internal network resources, including sensitive metadata services in cloud environments. This could result in exposure of confidential information, internal service enumeration, and potential lateral movement within corporate networks. Given that Nexus Repository is often integrated into CI/CD pipelines and software supply chains, exploitation could disrupt development workflows or be leveraged for supply chain attacks. The requirement for administrator privileges reduces the risk of external attackers exploiting this vulnerability directly; however, insider threats or compromised credentials could enable exploitation. The medium severity rating reflects a moderate risk, but the strategic importance of software repositories in European industries such as automotive, finance, and technology increases the potential impact. Additionally, organizations relying on cloud infrastructure with metadata services accessible via SSRF are at heightened risk of credential theft or privilege escalation. Failure to mitigate this vulnerability could undermine trust in software supply chains and lead to regulatory compliance issues under GDPR if sensitive data is exposed.

1. Upgrade Nexus Repository to version 3.88.0 or later where the workaround configuration is available to restrict proxy repository URLs and prevent SSRF exploitation. 2. Implement strict validation and whitelisting of URLs used in proxy repository configurations to ensure only trusted destinations are accessible. 3. Enforce the principle of least privilege by limiting administrator access to Nexus Repository and regularly auditing administrative accounts and activities. 4. Segment the network to isolate Nexus Repository servers from sensitive internal resources and cloud metadata endpoints, reducing the attack surface. 5. Monitor Nexus Repository logs for unusual proxy repository configurations or access patterns indicative of SSRF attempts. 6. Employ multi-factor authentication (MFA) for administrative access to reduce the risk of credential compromise. 7. Conduct regular security assessments and penetration testing focused on SSRF and related vulnerabilities within development infrastructure. 8. Educate administrators about the risks of SSRF and the importance of secure configuration management.