DefaultFuction Jeson-Customer-Relationship-Management-System Server-Side Request Forgery Vulnerability

A server-side request forgery (SSRF) vulnerability, identified as CVE-2026-4623, has been discovered in DefaultFuction Jeson-Customer-Relationship-Management-System up to version 1b4679c4d06b90d31dd521c2b000bfdec5a36e00. The vulnerability resides within the API Module, specifically in the /api/System.php file. An attacker can remotely manipulate the ‘url’ argument, causing the server to make requests to unintended locations. Due to the product’s continuous delivery with rolling releases, specific version details are unavailable. A patch to address the vulnerability is identified as f76e7123fe093b8675f88ec8f71725b0dd186310/98bd4eb07fa19d4f2c5228de6395580013c97476. This vulnerability poses a significant risk as it allows attackers to potentially access internal resources, bypass security controls, and potentially escalate privileges.

Attack Chain

1. Attacker identifies an instance of DefaultFuction Jeson-Customer-Relationship-Management-System running version <= 1b4679c4d06b90d31dd521c2b000bfdec5a36e00.
2. Attacker crafts a malicious HTTP request targeting the /api/System.php endpoint.
3. The crafted request includes the url parameter, modified to point to an internal resource or external server controlled by the attacker.
4. The server-side application processes the malicious request without proper validation of the url parameter.
5. The application initiates an HTTP request to the attacker-controlled URL or internal resource specified in the url parameter.
6. The server receives the response from the attacker-controlled server or internal resource.
7. The application may process the response, potentially exposing sensitive information or allowing further exploitation.
8. If successful, the attacker gains access to sensitive information, internal resources, or the ability to perform actions on behalf of the server.

Impact

Successful exploitation of this SSRF vulnerability (CVE-2026-4623) can lead to the exposure of sensitive internal data, such as configuration files, database credentials, or API keys. It may also allow attackers to bypass security controls, access internal services not intended for public access, and potentially escalate privileges within the application or the underlying infrastructure. Due to lack of information on the specific scope of usage for this CRM, the total number of potential victims is unclear. Organizations utilizing this vulnerable CRM are at risk.

Recommendation

• Apply the patch identified as f76e7123fe093b8675f88ec8f71725b0dd186310/98bd4eb07fa19d4f2c5228de6395580013c97476 to mitigate the CVE-2026-4623 vulnerability.
• Deploy the Sigma rule “Detect Jeson CRM System.php SSRF Attempt” to your SIEM to detect exploitation attempts against the /api/System.php endpoint.
• Implement strict input validation and sanitization on the url parameter within the /api/System.php endpoint to prevent malicious URL manipulation.
• Monitor web server logs for suspicious requests to the /api/System.php endpoint, specifically those containing unusual or unexpected URLs in the url parameter, to identify potential exploitation attempts.