---
cve: "CVE-2026-33946"
severity: "HIGH"
cvss: 8.2
epss: "47%"
vendor: "modelcontextprotocol"
kev: false
exploited: false
published: "2026-03-27 22:16:21"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-19T13:12:28+02:00"
---

# CVE-2026-33946

> 8.2 HIGH · 🧪 PoC

## Beschreibung

MCP Ruby SDK is the official Ruby SDK for Model Context Protocol servers and clients. Prior to version 0.9.2, the Ruby SDK's streamable_http_transport.rb implementation contains a session hijacking vulnerability. An attacker who obtains a valid session ID can completely hijack the victim's Server-Sent Events (SSE) stream and intercept all real-time data. Version 0.9.2 contains a patch.

## CVSS-Vektor

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

- 3fc7bcd2683d2200d42f79ab46752dc65f896db1 (Commit)
- db40143402d65b4fb6923cec42d2d72cb89b3874 (Commit)

## Referenzen

- <https://github.com/modelcontextprotocol/ruby-sdk/security/advisories/GHSA-qvqr-5cv7-wh35>
- <https://github.com/modelcontextprotocol/ruby-sdk/commit/db40143402d65b4fb6923cec42d2d72cb89b3874>
- <https://hackerone.com/reports/3556146>
- <https://github.com/modelcontextprotocol/csharp-sdk/blob/main/src/ModelContextProtocol.AspNetCore/SseHandler.cs#L93-L97>
- <https://github.com/modelcontextprotocol/go-sdk/blob/main/mcp/streamable.go#L281C1-L288C2>
- <https://github.com/modelcontextprotocol/python-sdk/blob/main/src/mcp/server/streamable_http.py#L680-L685>
- <https://github.com/modelcontextprotocol/ruby-sdk/blob/main/examples/streamable_http_server.rb>
- <https://github.com/modelcontextprotocol/ruby-sdk/releases/tag/v0.9.2>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-33946) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_