---
cve: "CVE-2026-8466"
severity: "HIGH"
cvss: 8.2
epss: "0.4%"
vendor: "ninenines"
kev: false
exploited: false
published: "2026-05-13 19:17:30"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-21T09:23:00+02:00"
---

# CVE-2026-8466

> 8.2 HIGH · 🧪 PoC

## Beschreibung

Allocation of Resources Without Limits or Throttling vulnerability in ninenines cowboy allows denial of service via unbounded buffer accumulation in multipart header parsing.

cowboy_req:read_part/3 in src/cowboy_req.erl accumulates incoming request bytes into a Buffer binary with no upper-bound check. When cow_multipart:parse_headers/2 returns more or {more, Buffer2}, the function reads up to Length bytes (default 64 KB) from the request body and recurses with the enlarged buffer. There is no equivalent of the byte_size(Acc) > Length guard present in the sibling function read_part_body/4. An unauthenticated attacker can send a multipart/form-data request whose body never yields a complete header section — for example, a body that never contains the advertised boundary delimiter, or one whose header lines never contain \r\n\r\n — and force the server process to accumulate memory linearly with the bytes the protocol layer is willing to deliver. A handful of concurrent such uploads is sufficient to exhaust BEAM memory.

This issue affects cowboy from 2.0.0 before 2.15.0.

## CVSS-Vektor

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

- 3b9fb5214d70f1c4707a095c4193214bc12a7c36 (Commit)
- 5c6a2061b41bb5771c4659fac7d5a822dca5bafb (Commit)

## Referenzen

- <https://cna.erlef.org/cves/CVE-2026-8466.html>
- <https://osv.dev/vulnerability/EEF-CVE-2026-8466>
- <https://github.com/ninenines/cowboy/commit/5c6a2061b41bb5771c4659fac7d5a822dca5bafb>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-8466) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_