Hono vulnerabilities
18 known CVE vulnerabilities in Hono, translated and rated.
- CVE-2026-22818High
Hono is a web framework for JavaScript. Prior to 4.11.4, the JWK/JWKS JWT verification middleware had a flaw that allowed the algorithm from the JWT header to influence signature verification when the selected JWK did not define an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted.
- CVE-2026-22817High
Hono is a web framework for JavaScript. Prior to version 4.11.4, the JWT middleware for JWK/JWKS verification had a flaw where the JWT header's alg value could influence signature verification when the selected JWK did not explicitly specify an algorithm. This could enable JWT algorithm confusion and, in certain configurations, allow forged tokens to be accepted.
- GHSA-frvp-7c67-39w9Medium
Path traversal vulnerability in serve-static on Windows via encoded backslash (%5C) in the request path. On Windows hosts, an encoded backslash (%5C) decodes to \, which the Windows path treats as a directory separator.
- CVE-2026-69207Medium
Hono before version 4.12.34 has a ReDoS vulnerability in the built-in CORS middleware (hono/cors). During a preflight OPTIONS request, the middleware parses the Access-Control-Request-Headers header using a regular expression with quadratic complexity, which can cause long CPU consumption and block request processing. This affects the default configuration when allowHeaders is unset or empty.
- CVE-2026-71850Medium
A vulnerability in the Hono framework from version 3.8.0 to 4.12.33 affects memo() from hono/jsx, which retains the result of a server-side render and reuses it for later renders with equal props. Request-scoped values read inside the component are not part of the comparison, potentially causing a user to receive HTML rendered for another user's request. The issue is fixed in version 4.12.34.
- CVE-2026-71849Low
Hono is a web application framework supporting any JavaScript runtime. From 4.7.0 to 4.12.33, the proxy() function in hono/proxy does not remove response headers named by the origin's Connection header. Per RFC 9110, an intermediary must remove these headers before forwarding, but the function only removes standard hop-by-hop headers, potentially leading to disclosure of internal metadata.
- CVE-2026-71848Medium
A vulnerability in the Hono framework from version 4.12.0 to 4.12.33 affects the languageDetector middleware, which is vulnerable to algorithmic complexity denial of service when processing a crafted language tag with a large number of hyphen-separated subtags. The normalizeLanguage() function repeatedly calls parts.slice(0, i).join('-') for every possible prefix, causing quadratic processing growth. The issue is fixed in version 4.12.34.
- CVE-2026-56764Low
Hono before version 4.11.10 contains a timing attack vulnerability in the basicAuth and bearerAuth middlewares due to non-constant-time string comparison in the timingSafeEqual function. Attackers can exploit early termination of string equality checks to infer valid credentials through precise timing measurements.
- CVE-2026-56763Medium
A vulnerability in Hono before version 4.12.7 allows the __proto__ key in parseBody with the dot option enabled, permitting specially crafted form field names to create objects with __proto__ properties. When parsed results are merged into regular JavaScript objects using unsafe merge patterns, attackers can exploit this to achieve prototype pollution and modify object behavior.
- CVE-2026-59897Medium
In Hono framework versions 4.3.3 through 4.12.26, the AWS API Gateway v1 adapter incorrectly de-duplicates header values using substring comparison instead of exact match. This causes distinct repeated header values to be dropped, affecting the completeness of data processed by middleware or application logic.
- CVE-2026-59896Medium
In Hono framework versions 4.11.8 through 4.12.26, a vulnerability was found where context values are not isolated per request during server-side rendering (SSR). This allows data from another concurrent request to be used after an await statement in an async component.
- CVE-2026-59895Medium
Vulnerability in Hono framework (versions 4.0.0 to 4.12.26) in the cx() function from hono/css. The function composes class names from plain strings but marks the result as already escaped without HTML-escaping the input, allowing untrusted className values used in a JSX class attribute during server-side rendering to break out of the attribute and inject arbitrary markup.
- CVE-2025-71381Medium
A vulnerability in Hono before version 4.10.2 (fixed in 4.10.3) in the CORS middleware causes the Vary header from the incoming request to be copied into the response when the origin is not set to "*". An attacker can supply arbitrary Vary values that are reflected in the response, leading to cache key pollution and inconsistent CORS enforcement in environments relying on shared caches or proxies.
- CVE-2026-56762Medium
Hono before version 4.12.12 does not validate cookie names in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters. This can lead to malformed Set-Cookie header values.
- CVE-2026-39410Medium
Hono, a web framework supporting any JavaScript runtime, prior to version 4.12.12 has a vulnerability due to a discrepancy between browser cookie parsing and the parse() function, allowing cookie prefix protections to be bypassed and attacker-controlled cookies to override legitimate ones.
- CVE-2026-39409Medium
Hono prior to version 4.12.12 does not canonicalize IPv4-mapped IPv6 client addresses before applying IPv4 allow/deny rules in ipRestriction().
- CVE-2026-39408High
Hono prior to 4.12.12 contains a path traversal issue in toSSG() that allows files to be written outside the configured output directory during static site generation.
- CVE-2026-39407Medium
In Hono prior to version 4.12.12, a path handling inconsistency in serveStatic allows access to protected static files by using repeated slashes (//) in the request path. This can lead to a bypass of route-based authorization.

