CVE-2026-54478 (GCVE-0-2026-54478)
Vulnerability from cvelistv5 – Published: 2026-07-22 13:09 – Updated: 2026-07-22 14:14
VLAI
EPSS
VEX
Title
DNS Cookie bypass when combined with proxy-protocol use
Summary
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.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-07-22 14:14 UTC
CWE
- CWE-290 - Authentication Bypass by Spoofing
Assigner
NLnet Labs
CNA
References
1 reference
| URL | Tags |
|---|---|
| https://www.nlnetlabs.nl/downloads/unbound/CVE-20… | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| NLnet Labs | Unbound |
Affected:
1.18.0 , < 1.25.2
(semver)
|
guessed |
Date Public
2026-07-22 00:00
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