SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityDeferred

CVE-2025-6515

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.

MEDIUM 6.8EPSS 0.37%

Does this matter?

Lower severity and a low EPSS score (0.37%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1
6.8 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H
EPSS
0.37% probability · 31th percentile
CISA KEV
Not listed
Weakness
CWE-330
Source
reefs@jfrog.com

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.