CVE-2026-54289 | Hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda@Edge, CloudFront delivers a request header that appears more than once as several separate entries. The adapter writes each value with Headers.set instead of Headers.append, so every value overwrites the previous one and only the last reaches the application. Repeated request headers such as X-Forwarded-For, Forwarded, and Via are silently truncated to a single value. Request middleware sees only the last value of a repeated header instead of the full chain. For applications that base access control on the X-Forwarded-For chain, this can weaken or alter that decision; for auditing, hop history is lost. This vulnerability is fixed in 4.12.25.

Published: 2026-06-22 Last update: 2026-06-22 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-54289 is rated Low Risk (19.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.11%). Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-54289

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-23 0.01% 0.11% +0.10%
2 2026-06-13 — 0.01% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-54289

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.2 2.5 [email protected]

Weakness enumeration for CVE-2026-54289

GitHub Security Advisory for CVE-2026-54289

GHSA-wgpf-jwqj-8h8p · Severity: medium · Ecosystem: npm — hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest

Affected software / configurations for CVE-2026-54289

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2026-54289

cvelogic Threat Intelligence