Open Source Social Network (OSSN) is open-source social networking software developed in PHP. Versions prior to 9.0 are vulnerable to resource exhaustion. An attacker can upload a specially crafted image with extreme pixel dimensions (e.g., $10000 \times 10000$ pixels). While the compressed file size on disk may be small, the server attempts to allocate significant memory and CPU cycles during the decompression and resizing process, leading to a Denial of Service (DoS) condition. It is highly recommended to upgrade to OSSN 9.0. This version introduces stricter validation of image dimensions and improved resource management during the processing phase. Those who cannot upgrade immediately can mitigate the risk by adjusting their `php.ini` settings to strictly limit `memory_limit` and `max_execution_time` and/or implementing a client-side and server-side check on image headers to reject files exceeding reasonable pixel dimensions (e.g., $4000 \times 4000$ pixels) before processing begins.

OSSN (Open Source Social Network) 8.6 is vulnerable to SQL Injection in /action/rtcomments/status via the timestamp parameter.

Open Source Social Network (OSSN) 8.6 is vulnerable to Cross Site Scripting (XSS) via the parameter param` at endpoint u/administrator/friends.

An issue was discovered in Open Source Social Network (OSSN) through 5.3. A user-controlled file path with a weak cryptographic rand() can be used to read any file with the permissions of the webserver. This can lead to further compromise. The attacker must conduct a brute-force attack against the SiteKey to insert into a crafted URL for components/OssnComments/ossn_com.php and/or libraries/ossn.lib.upgrade.php.