---
cve: "CVE-2026-54478"
severity: "LOW"
cvss: 3.7
epss: "18%"
vendor: "NLnet Labs"
kev: false
exploited: false
published: "2026-07-22 14:17:21"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T14:41:45+02:00"
---

# CVE-2026-54478

> 3.7 LOW

## Beschreibung

In NLnet Labs Unbound 1.18.0 up to and including 1.25.1, when Unbound listens on a 'proxy-protocol-port' interface with 'answer-cookie: yes', the RFC 9018 server-cookie SipHash is computed over the proxy's wire address instead of the PROXYv2-declared client. One server cookie obtained through a given proxy node therefore validates for every PROXYv2-declared source behind that node. On a UDP+proxy-protocol front, an off-path attacker can harvest one cookie with a single legitimate query, then replay it under any spoofed source and pass DNS Cookie checks that were deployed to defeat this in the first place.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- c33ad1b1a21e48bfe4f140e90252a9be1b0c5745 (Commit)

## Referenzen

- <https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-54478.txt>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-54478) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_