Medium severity · published Jul 8, 2026
CVE-2026-59897
Hono: API Gateway v1 adapter can drop a distinct repeated request header value during de-duplication
5.3
CVSS
0.2%
EPSS
No
On KEV
Description
Hono is a Web application framework that provides support for any JavaScript runtime. From 4.3.3 before 4.12.27, the AWS API Gateway v1 adapter can drop a distinct repeated request header value because it de-duplicates values using a substring comparison instead of an exact match, so middleware or application logic that depends on the complete X-Forwarded-For chain, rate limiting, audit logging, or proxy-chain validation can receive incomplete data. This issue is fixed in version 4.12.27.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hono · honojs
>= 4.3.3, < 4.12.27 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-59897
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-59897
Patch
https://github.com/honojs/hono/commit/aa921770d09bc35970362d5a2630a878f6d982fd
Release Notes
https://github.com/honojs/hono/releases/tag/v4.12.27
Vendor Advisory
https://github.com/honojs/hono/security/advisories/GHSA-xgm2-5f3f-mvvc
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