CVE-2026-54478
LOW
3.7
CVSS 3.1
Description
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.
Metadata
Severity & Metrics
3.7
LOW CVSS 3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
SSVC — CISA Coordinator
Affected products (1)
| Vendor | Product | Platform | Versions |
|---|---|---|---|
| NLnet Labs | Unbound | — | 1.18.0 < 1.25.2 |
Weakness (CWE)
| CWE | Source | Description |
|---|---|---|
| CWE-290 | cna | CWE-290: Authentication Bypass by Spoofing |
CVSS scores (1)
| Score | Severity | Version | Source | Vector |
|---|---|---|---|---|
| 3.7 | LOW | 3.1 | cna | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |