{"id":"CVE-2026-59897","aliases":["GHSA-xgm2-5f3f-mvvc"],"url":"https://o3.security/vulnerability/CVE-2026-59897","summary":"Hono: API Gateway v1 adapter can drop a distinct repeated request header value during de-duplication","details":"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.","published":"2026-07-08T16:06:11.369Z","modified":"2026-08-12T03:51:08.239919066Z","cvss":{"score":4.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N"},"epss":{"score":0.0018,"percentile":0.07554,"asOf":"2026-09-03"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"hono","fixedVersion":"4.12.27"}],"fix":{"url":"https://github.com/honojs/hono/commit/aa921770d09bc35970362d5a2630a878f6d982fd","label":"honojs/hono@aa92177"},"references":[{"type":"WEB","url":"https://github.com/honojs/hono/releases/tag/v4.12.27"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59897.json"},{"type":"ADVISORY","url":"https://github.com/honojs/hono/security/advisories/GHSA-xgm2-5f3f-mvvc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59897"},{"type":"FIX","url":"https://github.com/honojs/hono/commit/aa921770d09bc35970362d5a2630a878f6d982fd"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:08.239919066Z"}}