{"id":"GHSA-54fx-42gc-7vw4","revision":"664ffd39b6954147a7188a6cb7a0d396","records":[{"revision":"664ffd39b6954147a7188a6cb7a0d396","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-54fx-42gc-7vw4","aliases":["CVE-2026-71848"],"title":"Hono: Algorithmic Complexity DoS in Language Middleware","description":"### Summary\n\nThe `languageDetector` middleware is vulnerable to algorithmic complexity denial of service when processing a crafted language tag containing a large number of hyphen-separated subtags.\n\n### Details\n\nTo implement progressive language-tag truncation, `normalizeLanguage()` repeatedly calls `parts.slice(0, i).join('-')` for every possible prefix. The total amount of string processing grows quadratically with the number of subtags.\n\nLanguage values may come from a query parameter, cookie, `Accept-Language` header, or URL path, depending on the detector configuration. The default detector order enables query-string, cookie, and header detection, so applications using `languageDetector()` may expose this processing to unauthenticated requests.\n\nRequest-size limits reduce the maximum cost of a single request but do not eliminate the issue. Inputs accepted by common JavaScript runtimes can still cause noticeable synchronous event-loop blocking.\n\n### Impact\n\nAn attacker may repeatedly send requests containing long, hyphen-separated language tags, causing excessive CPU consumption and preventing unrelated requests from being processed.\n\nThe practical impact depends on the runtime's request-size limits, reverse-proxy configuration, and the detectors enabled by the application.\n\n### Resolution\n\nThe progressive lookup should avoid reconstructing every shorter prefix. The implementation can instead inspect the configured supported languages and select the longest value that matches the input at a hyphen boundary.","state":0,"publishedAt":"2026-08-07T18:36:31+00:00","modifiedAt":"2026-09-10T03:50:53.3114386+00:00","affected":[{"ecosystem":"npm","name":"hono","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"4.12.0"},{"kind":"fixed","version":"4.12.34"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/honojs/hono/security/advisories/GHSA-54fx-42gc-7vw4","https://github.com/honojs/hono/commit/f70e2c31684387b3231cc38512a31df6ca76a1c7","https://github.com/honojs/hono","https://github.com/honojs/hono/releases/tag/v4.12.34"],"sourceUrl":"https://github.com/advisories/GHSA-54fx-42gc-7vw4","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-54fx-42gc-7vw4","identifiers":["GHSA-54fx-42gc-7vw4","CVE-2026-71848"]},"retained":false,"historicalAffected":[]}],"coverage":[]}