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.
CVE-2026-54478
LOWPre-NVD 3.73.7—Trending — 4 sources updated this week
EchelonGraph scoreHIGH confidence
Score 3.7 from GitHub Security Advisory (severity: LOW) published 2026-07-22. a secondary CVSS source baseline 3.7; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, secondary
3.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 3.7Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 3.7
- EG Score
- 3.7(high)
- EG Risk
- 17(Track)EG Risk 17/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity37% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 15.5%
- KEV
- Not listed
Published
July 22, 2026
Last Modified
July 22, 2026
References (1)
Vendor Advisories for CVE-2026-54478(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 03:19 UTCEG score recompute
- 2026-07-22 22:02 UTCEG score recompute
- 2026-07-22 22:01 UTCGHSA enrichment
- 2026-07-22 17:15 UTCEG score recompute
- 2026-07-22 17:15 UTCGHSA enrichment
- 2026-07-22 14:55 UTCEG score recompute
- 2026-07-22 13:17 UTCEG score recompute
- 2026-07-22 13:17 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-290
Frequently asked(5)
What is CVE-2026-54478?
CVE-2026-54478 is a low vulnerability published on July 22, 2026. 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…
When was CVE-2026-54478 disclosed?
CVE-2026-54478 was first published in the National Vulnerability Database on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-54478 actively exploited?
CVE-2026-54478 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 15.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-54478?
CVE-2026-54478 has a CVSS v3 base score of 3.7 (NVD).
How do I remediate CVE-2026-54478?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54478, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-54478
Is Your Infrastructure Affected by CVE-2026-54478?
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