---
cve: "CVE-2026-34827"
severity: "HIGH"
cvss: 7.5
epss: "0.5%"
vendor: "rack"
kev: false
exploited: false
published: "2026-04-02 18:16:33"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T18:30:25+02:00"
---

# CVE-2026-34827

> 7.5 HIGH · 🧪 PoC

## Beschreibung

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 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)

- ae8431120e66e92d1885ab8ec0a553d9cad5ec13 (Commit)
- e1f22fdbe99afd2126b6fbf05bb12399359574b7 (Commit)

## Referenzen

- <https://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x>
- <https://access.redhat.com/security/cve/CVE-2026-34827>
- <https://bugzilla.redhat.com/show_bug.cgi?id=2454501>
- <https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34827.json>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-34827) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_