{"cve":"CVE-2026-71848","nvd":{"published":"2026-08-07T19:18:53.950","modified":"2026-10-24T15:10:00.190","status":"Deferred","description":"Hono is a Web application framework that provides support for any JavaScript runtime. From 4.12.0 to 4.12.33, the languageDetector middleware is vulnerable to algorithmic complexity denial of service when processing a crafted language tag containing a large number of hyphen separated subtags. To implement progressive language tag truncation, normalizeLanguage() repeatedly calls parts.slice(0, i).join('-') for every possible prefix, so the total amount of string processing grows quadratically with the number of subtags. Language values may come from a query parameter, cookie, Accept-Language header, or URL path, depending on the detector configuration, and the default detector order enables query string, cookie, and header detection, so applications using languageDetector() may expose this processing to unauthenticated requests. An attacker may repeatedly send requests containing long, hyphen separated language tags, causing excessive CPU consumption and preventing unrelated requests from being processed. This issue is fixed in version 4.12.34.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-407"],"references":["https://github.com/honojs/hono/commit/f70e2c31684387b3231cc38512a31df6ca76a1c7","https://github.com/honojs/hono/releases/tag/v4.12.34","https://github.com/honojs/hono/security/advisories/GHSA-54fx-42gc-7vw4"],"products":[],"source":"nvd","synced_at":"2026-10-24T16:53:34.184483516+00:00"},"epss":{"cve":"CVE-2026-71848","score":0.00507,"percentile":0.42952,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-54fx-42gc-7vw4","url":"https://osv.dev/vulnerability/GHSA-54fx-42gc-7vw4","summary":"Hono: Algorithmic Complexity DoS in Language Middleware","modified":"2026-09-10T03:50:53.311438629Z","packages":[{"ecosystem":"npm","name":"hono","purl":"pkg:npm/hono","ranges":[">=4.12.0 <4.12.34"],"fixed":["4.12.34"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}