---
cve: "CVE-2026-34829"
severity: "HIGH"
cvss: 7.5
epss: "37%"
vendor: "rack"
kev: false
exploited: false
published: "2026-04-02 17:16:26"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-17T04:49:52+02:00"
---

# CVE-2026-34829

> 7.5 HIGH · 🧪 PoC

## Beschreibung

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- f2af0c8f869193fa7bb7d20b619b3003418e1055 (Commit)
- ae8431120e66e92d1885ab8ec0a553d9cad5ec13 (Commit)

## Referenzen

- <https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw>
- <https://access.redhat.com/security/cve/CVE-2026-34829>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2454488>
- <https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34829.json>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-34829) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_