CVE-2026-63306 in stoatchat
Summary
by MITRE • 07/16/2026
stoatchat before 0.13.5 contains an unauthenticated server-side request forgery vulnerability in the /proxy and /embed endpoints that accept arbitrary URLs without DNS resolution filtering or private IP range validation. Attackers can enumerate internal services, fingerprint applications, and reach instance metadata endpoints by supplying malicious URLs or leveraging redirect chains to access internal infrastructure.
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Analysis
by VulDB Data Team • 07/16/2026
The stoatchat application prior to version 0.13.5 presents a critical server-side request forgery vulnerability that fundamentally compromises the security boundaries of affected systems. This vulnerability exists within the /proxy and /embed endpoints where the application accepts arbitrary URLs without implementing any form of DNS resolution filtering or private IP address range validation. The flaw allows unauthorized attackers to submit malicious URLs that bypass normal network access controls and potentially gain access to internal services that would otherwise be protected by firewalls or network segmentation. The vulnerability operates at the application layer where the software fails to validate or sanitize input URLs before processing them, creating a pathway for attackers to indirectly access resources within the internal network that should remain isolated from external access.
This particular flaw aligns with common security weaknesses identified in CWE-918, which specifically addresses server-side request forgery vulnerabilities where applications fail to properly validate and filter user-supplied URLs. The vulnerability enables attackers to perform reconnaissance activities including internal service enumeration and application fingerprinting by leveraging the application's ability to make HTTP requests to internal endpoints. Through carefully crafted URL inputs or redirect chains, adversaries can potentially reach instance metadata endpoints that contain sensitive information about cloud infrastructure, system configurations, and authentication tokens. The absence of proper IP range validation means that attackers can target private network addresses that are typically protected from direct internet access, effectively bypassing network-level security controls.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential privilege escalation and lateral movement within compromised environments. Attackers can use the vulnerability to map internal network topology, identify running services on internal hosts, and potentially access sensitive resources such as databases, configuration files, or administrative interfaces that are normally protected by internal firewalls. The ability to leverage redirect chains significantly amplifies the attack surface since a single vulnerable endpoint can be used to reach multiple internal targets through a series of redirects. This type of vulnerability is particularly concerning in cloud environments where instance metadata services contain critical credentials and configuration data that attackers can exploit for further compromise.
Security professionals should implement immediate mitigations including input validation for all URL parameters, implementation of private IP range filtering, and DNS resolution checks to prevent access to internal network addresses. The recommended approach involves configuring the application to reject URLs containing private IP ranges such as 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, and loopback addresses. Network-level controls should also be deployed to prevent outbound connections from the application server to internal network segments. Organizations should consider implementing a whitelist approach for allowed URLs or employing dedicated proxy services that enforce strict access controls on external requests. The vulnerability demonstrates the importance of adhering to secure coding practices as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1071.004 which covers application layer protocol usage for command and control communications. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other applications within the attack surface, ensuring that similar weaknesses do not exist in related components or services that may provide access to internal infrastructure through alternative pathways.