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CVE-2025-6515Reuse of session IDs in oatpp-mcp leads to session hijacking and prompt hijacking by remote attackers
- 6.8MediumCVSS base score
- 0.40%Exploitation in 30 daysEPSS · top 65% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
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.
Timeline
ID reserved
By JFROG
- 4 months later
· 4 months later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| JFROGCNA (assigner) | 3.1 | Medium6.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H |
| NVDNVD · Deferred | 3.1 | Medium6.8 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.40% · top 65% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.8.
Affected products
References
References1
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-35077 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-6515)Record last updated .