CVE-2026-0600 Overview
A Server-Side Request Forgery (SSRF) vulnerability exists in Sonatype Nexus Repository 3 versions 3.0.0 and later. This vulnerability allows authenticated administrators to configure proxy repositories with URLs that can access unintended network destinations, potentially including cloud metadata services and internal network resources. While a workaround configuration is available starting in version 3.88.0, the product remains vulnerable by default.
Critical Impact
Authenticated administrators can exploit SSRF to access cloud metadata services (such as AWS IMDSv1, Azure IMDS, or GCP metadata endpoints) and internal network resources, potentially leading to credential theft or further network compromise.
Affected Products
- Sonatype Nexus Repository 3 versions 3.0.0 and later
- All configurations using proxy repositories prior to applying the workaround
- Default configurations in version 3.88.0 and later (vulnerable until workaround is applied)
Discovery Timeline
- 2026-01-14 - CVE-2026-0600 published to NVD
- 2026-01-16 - Last updated in NVD database
Technical Details for CVE-2026-0600
Vulnerability Analysis
This SSRF vulnerability (CWE-918) exists in the proxy repository configuration functionality of Sonatype Nexus Repository 3. When administrators configure proxy repositories, the application does not adequately validate or restrict the target URLs that can be specified. This allows an attacker with administrative privileges to configure proxy repositories pointing to internal network addresses or cloud provider metadata endpoints.
The attack requires authenticated access with administrator-level privileges, which limits the attack surface but doesn't eliminate the risk in environments where administrative accounts may be compromised or where insider threats exist. In cloud environments, successful exploitation could allow access to instance metadata services, potentially exposing temporary credentials, API keys, and other sensitive configuration data.
Root Cause
The root cause of this vulnerability is insufficient URL validation in the proxy repository configuration workflow. The application fails to implement adequate restrictions on destination URLs, allowing administrators to specify internal IP addresses, localhost references, link-local addresses (169.254.x.x), and cloud metadata service endpoints. This lack of server-side validation enables SSRF attacks that can reach otherwise protected internal resources.
Attack Vector
An attacker with administrative credentials can exploit this vulnerability through the following approach:
- Authenticate to the Nexus Repository administration interface
- Navigate to proxy repository configuration settings
- Configure a new proxy repository or modify an existing one
- Specify a malicious URL targeting internal resources (e.g., http://169.254.169.254/latest/meta-data/ for AWS metadata)
- Trigger a request through the proxy repository to retrieve sensitive data from the targeted internal resource
The vulnerability can be exploited to access cloud metadata services that may contain temporary IAM credentials, access private network services, or perform reconnaissance on internal network topology.
Detection Methods for CVE-2026-0600
Indicators of Compromise
- Proxy repository configurations pointing to internal IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x)
- Proxy repositories configured with cloud metadata service URLs (169.254.169.254, metadata.google.internal)
- Unusual outbound requests from the Nexus Repository server to internal network destinations
- Access logs showing requests to localhost or loopback addresses (127.0.0.1)
Detection Strategies
- Audit all proxy repository configurations for URLs targeting private IP address ranges or metadata endpoints
- Monitor network traffic from Nexus Repository servers for connections to internal-only services
- Implement alerting for configuration changes to proxy repositories
- Review administrative access logs for unauthorized or suspicious configuration modifications
Monitoring Recommendations
- Enable detailed audit logging for all administrative actions in Nexus Repository
- Deploy network monitoring to detect SSRF-related traffic patterns from repository servers
- Implement file integrity monitoring on Nexus Repository configuration files
- Establish baseline behavior for outbound connections and alert on anomalies
How to Mitigate CVE-2026-0600
Immediate Actions Required
- Review all existing proxy repository configurations for potentially malicious URLs
- Upgrade to Sonatype Nexus Repository version 3.88.0 or later to access the workaround configuration
- Apply the workaround configuration as described in the vendor's support documentation
- Audit administrative account access and implement least-privilege principles
Patch Information
Sonatype has provided a workaround configuration starting in version 3.88.0, though the product remains vulnerable by default. Organizations should consult the Sonatype Support Article for detailed instructions on implementing the protective configuration.
Workarounds
- Implement the workaround configuration available in version 3.88.0 and later as documented by Sonatype
- Restrict network egress from Nexus Repository servers using firewall rules to block access to cloud metadata services and internal resources
- Deploy a web application firewall (WAF) to inspect and block SSRF-related requests
- Limit administrative access to trusted personnel and implement multi-factor authentication for admin accounts
- Consider network segmentation to isolate the Nexus Repository server from sensitive internal resources
# Network-level mitigation example using iptables
# Block outbound access to common cloud metadata endpoints from the Nexus server
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 169.254.170.2 -j DROP
# Block access to internal network ranges (adjust based on your environment)
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
