{"id":"CVE-2026-71848","revision":null,"records":[{"revision":"5a1644a774ff41a1bf8b0746f84633d1","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-71848","aliases":[],"title":"Hono: Algorithmic Complexity DoS in Language Middleware","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.","state":0,"publishedAt":"2026-08-07T18:36:16.872+00:00","modifiedAt":"2026-08-08T03:04:43.996+00:00","affected":[{"ecosystem":"Vendor product","name":"hono","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"honojs\",\n                    \"product\": \"hono\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 4.12.0, < 4.12.34\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 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,"severity":"MEDIUM"}],"references":["https://github.com/honojs/hono/security/advisories/GHSA-54fx-42gc-7vw4","https://github.com/honojs/hono/commit/f70e2c31684387b3231cc38512a31df6ca76a1c7","https://github.com/honojs/hono/releases/tag/v4.12.34"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-71848","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-71848","identifiers":["CVE-2026-71848"]},"retained":false,"historicalAffected":[]},{"revision":"26c74d80d6cb467bac450f2e63172bf3","observedAt":"2026-10-25T15:18:57.446+00:00","statement":{"source":"nvd","id":"CVE-2026-71848","aliases":[],"title":"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 c…","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.","state":0,"publishedAt":"2026-08-07T19:18:53.95+00:00","modifiedAt":"2026-10-24T15:10:00.19+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3,"severity":"MEDIUM"}],"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"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-71848","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-407"],"productCriteria":[],"sourceDates":{"published":"2026-08-07T19:18:53.950","lastModified":"2026-10-24T15:10:00.190"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-71848","identifiers":["CVE-2026-71848"]},"retained":false,"historicalAffected":[]},{"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":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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