CVE-2025-15414: go-sonic SSRF Vulnerability

CVE-2025-15414 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in go-sonic sonic up to version 1.1.4. The vulnerability exists in the FetchTheme function within the service/theme/git_fetcher.go file of the Theme Fetching API component. An attacker can manipulate the uri argument to force the server to make arbitrary requests to internal or external resources, potentially exposing sensitive data or enabling further attacks on internal infrastructure.

Critical Impact

Authenticated attackers with high privileges can exploit this SSRF vulnerability remotely to access internal network resources, potentially bypassing security controls and exfiltrating sensitive information.

Affected Products

• go-sonic sonic versions up to and including 1.1.4
• Applications utilizing the Theme Fetching API component
• Deployments exposing the FetchTheme functionality to authenticated users

Discovery Timeline

• 2026-01-01 - CVE-2025-15414 published to NVD
• 2026-01-02 - Last updated in NVD database

Technical Details for CVE-2025-15414

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The FetchTheme function in go-sonic's Theme Fetching API fails to properly validate user-supplied URI inputs before making server-side requests. When a privileged user provides a malicious URI parameter, the application processes it without adequate sanitization, allowing the attacker to direct the server to make requests to arbitrary destinations.

SSRF vulnerabilities of this nature can be particularly dangerous in cloud environments where internal metadata services (such as AWS IMDSv1) may be accessible. The vulnerability requires high privileges to exploit, which limits the attack surface but still poses significant risk in multi-tenant environments or scenarios where administrative credentials are compromised.

Root Cause

The root cause lies in insufficient input validation within the FetchTheme function in service/theme/git_fetcher.go. The function accepts a user-controlled uri parameter and uses it to fetch theme resources without implementing proper URL validation, allowlist filtering, or scheme restrictions. This allows attackers to craft malicious URIs that target internal services, local files, or cloud metadata endpoints.

Attack Vector

The vulnerability is exploitable over the network by authenticated users with elevated privileges. An attacker can craft HTTP requests to the Theme Fetching API endpoint with specially crafted uri parameters pointing to internal resources such as:

• Internal network services (e.g., http://192.168.1.1/admin)
• Cloud metadata endpoints (e.g., http://169.254.169.254/latest/meta-data/)
• Local services (e.g., http://localhost:8080/internal-api)

The exploit has been publicly disclosed and proof-of-concept details are available. Additional technical information can be found in the HXLab PoC Document and VulDB #339335.

Detection Methods for CVE-2025-15414

Indicators of Compromise

• Unusual outbound requests from the go-sonic server to internal IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Requests to cloud metadata endpoints (169.254.169.254) originating from the application server
• Theme Fetching API calls with suspicious URI parameters containing localhost, internal hostnames, or non-standard ports
• Unexpected HTTP traffic patterns from the server to previously uncontacted internal services

Detection Strategies

• Implement network monitoring to detect outbound connections from the go-sonic application to internal network ranges
• Configure Web Application Firewall (WAF) rules to inspect and block Theme Fetching API requests containing suspicious URI patterns
• Enable verbose logging on the FetchTheme function to capture all URI parameter values for security review
• Deploy endpoint detection and response (EDR) solutions to monitor for anomalous network behavior from application servers

Monitoring Recommendations

• Monitor application logs for Theme Fetching API requests with non-standard URI schemes or internal IP addresses
• Set up alerts for any connections to cloud metadata services from application servers
• Implement network segmentation monitoring to detect lateral movement attempts initiated via SSRF
• Review DNS query logs for unusual internal hostname resolution requests from the go-sonic server

How to Mitigate CVE-2025-15414

Immediate Actions Required

• Upgrade go-sonic to a version newer than 1.1.4 if a patched version becomes available
• Implement network-level controls to restrict outbound connections from the go-sonic server
• Apply URL allowlisting for the Theme Fetching API to limit permitted destinations
• Review and restrict privileges for users with access to the Theme Fetching functionality
• Consider disabling the Theme Fetching API if not required for operations

Patch Information

At the time of publication, the vendor was contacted about this vulnerability but did not respond. No official patch is currently available. Organizations should monitor the VulDB entry and go-sonic project for security updates. Until an official fix is released, implementing the workarounds below is strongly recommended.

Workarounds

• Implement a strict URL allowlist that only permits fetching themes from trusted, explicitly defined external sources
• Deploy a forward proxy with URL filtering to control and inspect all outbound requests from the application server
• Use network segmentation to isolate the go-sonic server and restrict its access to internal resources
• Disable the Theme Fetching API feature entirely if not critical to business operations
• Implement rate limiting on the Theme Fetching API to slow potential exploitation attempts

# Example: Network-level mitigation using iptables to block internal network access
# Block access to common internal ranges from the go-sonic application user

# Block RFC1918 private ranges
iptables -A OUTPUT -m owner --uid-owner go-sonic -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -m owner --uid-owner go-sonic -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -m owner --uid-owner go-sonic -d 192.168.0.0/16 -j DROP

# Block cloud metadata endpoint
iptables -A OUTPUT -m owner --uid-owner go-sonic -d 169.254.169.254 -j DROP

# Block localhost access
iptables -A OUTPUT -m owner --uid-owner go-sonic -d 127.0.0.0/8 -j DROP