---
cve: "CVE-2026-67431"
severity: "HIGH"
cvss: 8.3
epss: "28%"
vendor: "modelcontextprotocol"
kev: false
exploited: false
published: "2026-07-29 19:15:32"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T10:27:05+02:00"
---

# CVE-2026-67431

> 8.3 HIGH · 🧪 PoC

## Beschreibung

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to 0.23.0, MCP::Server::Transports::StreamableHTTPTransport in the mcp gem does not bind a session ID to a session owner, allowing an attacker with a stolen session ID to send tools/call requests that execute in the victim's session. This issue is fixed in version 0.23.0.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 35466605319a34e4c7808712ae9bb1ca1afb2356 (Commit)
- 95feef2dcfba25d92a8963d14b7a3b279122f36f (Commit)

## Referenzen

- <https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-5p9g-j988-pcwv>
- <https://github.com/modelcontextprotocol/ruby-sdk/commit/35466605319a34e4c7808712ae9bb1ca1afb2356>
- <https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.23.0>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-67431) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_