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 memorylimit and maxexecutiontime 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.

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

Open Source Social Network (OSSN) through 10.1 contains an insecure direct object reference vulnerability in components/OssnMessages/ossncom.php that allows authenticated users to read other users' private message attachments. Attackers can request the /messages/attachment/{guid} route with sequential or guessed file GUIDs to retrieve attachments from private conversations without sender or recipient verification.