Attack Chain

1. An attacker identifies a NextChat instance running a vulnerable version (<= 2.16.1).
2. The attacker crafts a malicious HTTP request targeting the app/api/[provider]/[...path]/route.ts endpoint.
3. The crafted request manipulates the proxyHandler function parameters.
4. The proxyHandler function, without proper validation, forwards the manipulated request to an internal server or resource.
5. The internal server processes the request as if it originated from the NextChat server itself.
6. The internal server returns the response to the NextChat server.
7. The NextChat server forwards the response from the internal server back to the attacker.
8. The attacker gains access to potentially sensitive information or can interact with internal services due to the SSRF vulnerability.

Impact

Successful exploitation of this SSRF vulnerability allows attackers to potentially access internal resources, including sensitive data or internal services not intended for public access. While the CVSS score is 7.3 (HIGH), the impact is limited to information disclosure and limited modification/availability of resources. The number of affected instances is currently unknown. If successfully exploited, attackers could potentially use the compromised NextChat instance as a proxy to further compromise the internal network.

Recommendation

• Apply input validation and sanitization to the proxyHandler function within app/api/[provider]/[...path]/route.ts to prevent malicious manipulation (Reference: CVE-2026-7177).
• Monitor web server logs for unusual requests targeting the app/api endpoint with potentially malicious parameters (See example Sigma rule below).
• Implement network segmentation to restrict access from the NextChat server to only necessary internal resources (General security best practice related to SSRF).
• Deploy the Sigma rules provided to detect exploitation attempts against NextChat instances.