CVE-2026-71848
Received
Received - Intake
Hono Framework LanguageDetector DoS via Hyphenated Tags
Vulnerability report for CVE-2026-71848, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-08-07
Last updated on: 2026-08-07
Assigner: GitHub, Inc.
Description
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 Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| honojs | hono | to 4.12.34 (exc) |
| honojs | hono | 4.12.34 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-407 | An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached. |
