Skip to content
Fencer Intel
medium 4.8

CVE-2026-59897 json

Hono: API Gateway v1 adapter can drop a distinct repeated request header value during de-duplication

published 4mo ago modified 17d ago also EUVD-2026-42325 , GHSA-xgm2-5f3f-mvvc

cvss
4.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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.

Patch / fix

  • npm hono 4.12.27
  • hono hono 4.12.27

Is CVE-2026-59897 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-59897 updated cvss 5.3

hono: Hono: Information disclosure due to incorrect header de-duplication in AWS API Gateway v1 adapter

  • Red Hat Migration Toolkit for Applications 8 mta/mta-solution-server-rhel9 Red Hat Ansible Automation Platform 2 ansible-automation-platform-27/mcp-server-rhel9, ansible-automation-platform-tech-preview/mcp-server-rhel9 Red Hat Developer Hub 1 rhdh/rhdh-hub-rhel9 Red Hat OpenShift Dev Spaces devspaces/code-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Hardened Images grafana12.4, grafana13.1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
GitHub 3.1 4.8 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
npm hono
>=4.3.3, <4.12.27
4.12.27

Affected products

  • honojs hono

Classification

Weakness
  • CWE-348 Use of Less Trusted Source

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of honojs/hono published their own advisory on GitHub. Reviewed sources take precedence over it.