CVE-2025-69206 is a Server-Side Request Forgery (SSRF) vulnerability identified in Hemmelig.app, a secure messaging application that provides client-side encryption and self-destructing messages. The vulnerability exists in versions prior to 7.3.3 within the webhook URL validation mechanism of the Secret Requests feature. Hemmelig.app attempts to prevent SSRF by blocking requests to internal or private IP addresses; however, this filtering can be bypassed using DNS rebinding or leveraging open redirect services. DNS rebinding tricks the server into resolving a domain name to an internal IP address after initial validation, while open redirects can redirect the server's HTTP requests to internal resources. An authenticated user can exploit this flaw to coerce the Hemmelig server to initiate HTTP requests to internal network endpoints that are otherwise inaccessible externally. This could allow attackers to probe internal services, gather sensitive information, or interact with internal APIs, potentially exposing confidential data. The vulnerability has a CVSS 3.1 base score of 4.3, reflecting a medium severity level. The attack vector is network-based, requires low privileges (authenticated user), and no user interaction is needed. The impact is limited to confidentiality, with no direct effect on integrity or availability. The vendor fixed this issue in version 7.3.3 by improving the validation logic to effectively block SSRF attempts. No public exploits have been reported to date. Organizations using Hemmelig.app should prioritize upgrading to the patched version to prevent potential internal network reconnaissance or data exposure via SSRF.

For European organizations, this SSRF vulnerability poses a moderate risk primarily to confidentiality. Attackers with valid user credentials could exploit the flaw to access internal network resources that are normally shielded from external access. This could lead to unauthorized information disclosure from internal services, such as intranet portals, internal APIs, or management interfaces. Although the vulnerability does not directly compromise message integrity or availability of the Hemmelig.app service, the ability to reach internal endpoints could facilitate further lateral movement or reconnaissance within the network. Organizations in sectors handling sensitive communications—such as government, finance, healthcare, and critical infrastructure—may face increased risk if internal systems are exposed via SSRF. The impact is somewhat mitigated by the requirement for authentication and the absence of known active exploits, but the potential for internal data leakage remains a concern. Prompt patching is essential to reduce exposure, especially in environments where Hemmelig.app is integrated into secure communication workflows.

1. Upgrade Hemmelig.app to version 7.3.3 or later immediately to apply the official patch that corrects the webhook URL validation and blocks SSRF bypass techniques. 2. Implement network segmentation and strict firewall rules to limit the Hemmelig server’s ability to initiate HTTP requests to sensitive internal resources, reducing the impact of any SSRF exploitation. 3. Monitor application logs and network traffic for unusual outbound HTTP requests originating from Hemmelig.app servers, which could indicate attempted SSRF exploitation. 4. Enforce strong authentication and access controls on the Hemmelig.app platform to minimize the risk of unauthorized users gaining the low-level privileges needed to exploit this vulnerability. 5. Conduct internal security assessments and penetration tests focusing on SSRF and related web vulnerabilities to identify and remediate similar weaknesses in other applications. 6. Educate users about the importance of applying updates promptly and maintaining vigilance for suspicious activity within secure messaging platforms.