CVE-2026-30835 affects parse-community's parse-server, an open-source backend framework running on Node.js. The vulnerability is due to improper handling of malformed $regex query parameters, such as unbalanced brackets (e.g., [abc), which cause the underlying database to generate structured error objects. These error objects contain sensitive internal information including error messages, error codes, code names, cluster timestamps, and topology details. The parse-server API previously passed these error objects directly to clients without sanitization, resulting in an information disclosure vulnerability classified under CWE-209 (Generation of Error Message Containing Sensitive Information). Since the vulnerability is triggered by malformed queries, any client capable of sending queries to the parse-server can exploit it without authentication or user interaction, contingent on the server's permission configuration. This leakage can aid attackers in reconnaissance and facilitate further targeted attacks. The vulnerability affects all parse-server versions prior to 8.6.7 and 9.5.0-alpha.6, where the issue has been patched. The CVSS v4.0 base score is 6.9, reflecting a medium severity with network attack vector, low complexity, and no privileges or user interaction required.

The primary impact of CVE-2026-30835 is unauthorized disclosure of sensitive internal database information through error messages. This information leakage can reveal database structure, error codes, cluster timestamps, and topology details, which attackers can leverage for reconnaissance to map the backend infrastructure and identify further vulnerabilities. While it does not directly allow code execution or data modification, the exposure of internal details increases the attack surface and can facilitate more sophisticated attacks such as injection, privilege escalation, or targeted exploitation of backend components. Organizations relying on parse-server for backend services risk exposing sensitive operational details to unauthenticated remote attackers, potentially undermining confidentiality and aiding in lateral movement within their infrastructure. The vulnerability's ease of exploitation and lack of required authentication make it a significant concern for any publicly accessible parse-server deployments.

To mitigate CVE-2026-30835, organizations should immediately upgrade parse-server to version 8.6.7 or later, or 9.5.0-alpha.6 or later, where the vulnerability is patched. Additionally, implement strict input validation and sanitization on all query parameters, especially those involving regular expressions, to prevent malformed queries from reaching the database layer. Configure API permissions to restrict query capabilities to authenticated and authorized users only, minimizing exposure to unauthenticated clients. Employ web application firewalls (WAFs) or API gateways to detect and block suspicious malformed queries that could trigger error leaks. Monitor logs for unusual query patterns or error message disclosures indicative of exploitation attempts. Finally, review and harden database error handling to ensure internal details are never exposed in API responses, applying the principle of least privilege and secure error reporting practices.