{"id":"CVE-2025-6515","aliases":["EUVD-2025-35077","GHSA-rvw9-mm8q-456q"],"status":"published","title":"Reuse of session IDs in oatpp-mcp leads to session hijacking and prompt hijacking by remote attackers","description":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not unique nor cryptographically secure. This allows network attackers with access to the oatpp-mcp server to guess future session IDs and hijack legitimate client MCP sessions, returning malicious responses from the oatpp-mcp server.","severity":{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00401,"percentile":0.34839,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-330"],"published":"2025-10-20T16:13:43Z","modified":"2026-10-08T22:10:00Z","products":[{"vendor":"oatpp","product":"oatpp-mcp"}],"references":[{"url":"https://research.jfrog.com/vulnerabilities/oatpp-mcp-prompt-hijacking-jfsa-2025-001494691/","tags":["third-party-advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-6515"},{"url":"https://research.jfrog.com/vulnerabilities/oatpp-mcp-prompt-hijacking-jfsa-2025-001494691"},{"url":"https://github.com/advisories/GHSA-rvw9-mm8q-456q"}],"sources":{"cve":[{"id":"CVE-2025-6515","title":"Reuse of session IDs in oatpp-mcp leads to session hijacking and prompt hijacking by remote attackers","description":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not unique nor cryptographically secure. This allows network attackers with access to the oatpp-mcp server to guess future session IDs and hijack legitimate client MCP sessions, returning malicious responses from the oatpp-mcp server.","status":"published","published":"2025-10-20T16:13:43.527Z","modified":"2025-10-20T16:33:47.787Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T14:32:40.419293Z"}],"euvd":[{"id":"EUVD-2025-35077","description":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not unique nor cryptographically secure. This allows network attackers with access to the oatpp-mcp server to guess future session IDs and hijack legitimate client MCP sessions, returning malicious responses from the oatpp-mcp server.","status":"published","published":"2025-10-20T16:13:43Z","modified":"2025-10-20T16:33:47Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H","level":"medium"}],"updated_at":"2026-11-02T20:31:29.921127Z"}],"ghsa":[{"id":"GHSA-rvw9-mm8q-456q","title":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not...","description":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not unique nor cryptographically secure. This allows network attackers with access to the oatpp-mcp server to guess future session IDs and hijack legitimate client MCP sessions, returning malicious responses from the oatpp-mcp server.","status":"published","published":"2025-10-20T18:30:35Z","modified":"2025-10-20T18:30:35Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H","level":"medium"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T15:04:01.823376Z"}],"nvd":[{"id":"CVE-2025-6515","description":"The MCP SSE endpoint in oatpp-mcp returns an instance pointer as the session ID, which is not unique nor cryptographically secure. This allows network attackers with access to the oatpp-mcp server to guess future session IDs and hijack legitimate client MCP sessions, returning malicious responses from the oatpp-mcp server.","status":"published","published":"2025-10-20T17:15:39.197Z","modified":"2026-10-08T22:10:00.563Z","cvss":[{"version":"3.1","score":6.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-330"],"updated_at":"2026-11-02T14:11:39.069866Z"}]}}