TI-2025-05915 Aliases CVE-2025-6515 GHSA-rvw9-mm8q-456q

Reuse of session IDs in oatpp-mcp leads to session hijacking and prompt hijacking by remote attackers

LOW 32CWE-330Published 2025-10-20 · Updated 2025-10-20

Key facts

Attack vector: Network
Privileges required: None
User interaction: Required
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: None · High · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00401 34th percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
oatpp	oatpp-mcp	all versions	—	No fix listed	CNA

oatpp-mcp Vendoroatpp Affected all versions Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

2026-10-02 Threatist record created from CVE-2025-6515
2026-10-03 Alias added: GHSA-rvw9-mm8q-456q

References

Advisory 1

https://research.jfrog.com/vulnerabilities/oatpp-mcp-prompt-hijacking-jfsa-2025-001494691/

TI-2025-05964 oatpp Oat++ Deserializer.cpp deserializeArray stack-based overflow CVSS 4.0MEDIUM 6.9

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences