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CVE-2025-6515

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

MEDIUM
6.8
CVSS Score
Published: October 20, 2025 at 04:13 PM UTC
Updated: October 8, 2026 at 10:10 PM UTC
1 product affected across 1 vendorOatpp Mcp

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Severity
MEDIUM6.8
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (1)

Third Party Advisory
Source: cverecord
https://research.jfrog.com/vulnerabilities/oatpp-mcp-prompt-hijacking-jfsa-2025-001494691/

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.8MEDIUMJFROG
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-330

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