CVE-2026-59895

Hono: Server-Side XSS via JSX Escaping Bypass in cx() Utility

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.0.0 before 4.12.27, cx() in hono/css 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. This issue is fixed in version 4.12.27.

CVSS 3.1 · 6.1 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-54287

Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda, the ALB single-header response and the VPC Lattice v2 response join multiple Set-Cookie headers into one comma-separated value. Because commas also appear inside cookie attributes (for example Expires dates), clients cannot split the value back into individual cookies and silently drop or misparse them. This vulnerability is fixed in 4.12.25.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-54286

Hono: Path traversal in `serve-static` on Windows via encoded backslash (`%5C`)

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on Windows hosts, an encoded backslash (%5C) in the request path decodes to \, which the Windows path resolver treats as a separator. serve-static then resolves a single URL segment such as admin\secret.txt into a nested file under the root and serves it, letting an attacker read static files meant to be protected behind prefix-mounted middleware. This vulnerability is fixed in 4.12.25.

CVSS 3.1 · 5.9 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-54290

Hono: CORS Middleware reflects any Origin with credentials when `origin` defaults to the wildcard

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, with credentials: true and no explicit origin (the default wildcard), the CORS Middleware reflects the request's Origin and sends Access-Control-Allow-Credentials: true. Any site can then make credentialed cross-origin requests and read the responses, exposing cookie-authenticated endpoints to arbitrary origins. This vulnerability is fixed in 4.12.25.

CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-54289

Hono: Lambda@Edge adapter keeps only the last value of a repeated request header, dropping the rest

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda@Edge, CloudFront delivers a request header that appears more than once as several separate entries. The adapter writes each value with Headers.set instead of Headers.append, so every value overwrites the previous one and only the last reaches the application. Repeated request headers such as X-Forwarded-For, Forwarded, and Via are silently truncated to a single value. Request middleware sees only the last value of a repeated header instead of the full chain. For applications that base access control on the X-Forwarded-For chain, this can weaken or alter that decision; for auditing, hop history is lost. This vulnerability is fixed in 4.12.25.

CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-54288

Hono: Body Limit Middleware can be bypassed on AWS Lambda by understating `Content-Length`

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, the Body Limit Middleware trusts the request's Content-Length header to decide whether a body is within the limit. On AWS Lambda (API Gateway v1/v2, ALB, VPC Lattice, and Lambda@Edge) the body is delivered fully buffered and the adapter builds the request with the client-declared Content-Length, which need not match the actual payload. A client can declare a tiny Content-Length while sending a much larger body, slipping past the limit. This vulnerability is fixed in 4.12.25.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-56761

hono - HTML Injection via Improper JSX Attribute Name Handling in SSR

hono before 4.12.14 contains an html injection vulnerability in jsx server-side rendering that allows attackers to inject unintended html by using malformed attribute names. Attackers can craft specially crafted attribute keys containing characters like quotes or angle brackets to break html tag boundaries and inject arbitrary attributes or elements.

CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-56762

Hono - Missing Cookie Name Validation in setCookie()

Hono before 4.12.12 does not validate cookie names on the write path in the setCookie(), serialize(), and serializeSigned() functions, allowing invalid characters such as control characters (e.g. \r or \n) when an application passes a user-controlled cookie name. This can produce malformed Set-Cookie header values. In modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and cause a runtime error before the response is sent, so header injection or response splitting could not be reproduced; the issue primarily affects correctness and robustness, resulting in runtime errors (availability) rather than confirmed header injection.

CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-47674

Hono: IP Restriction bypasses static deny rules for non-canonical IPv6

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the ip-restriction middleware (hono/ip-restriction) compares incoming IP addresses against configured deny and allow rules using string equality after partial normalization. Non-canonical IPv6 representations of an address already listed in a static rule — such as compressed forms, explicit-zero forms, or hex-notation IPv4-mapped addresses — do not match the normalized rule entry, causing the rule to be silently skipped. This vulnerability is fixed in 4.12.21.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-47673

Hono: JWT middleware accepts any Authorization scheme, not only Bearer

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the jwt and jwk middlewares do not verify that the Authorization header value uses theBearer scheme. Any two-part header value — regardless of the scheme name in the first position — proceeds to JWT verification. A request presenting a valid JWT under a non-Bearer scheme identifier (such as Basic or Token) is authenticated identically to a correctly formed Bearer request. This vulnerability is fixed in 4.12.21.

CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-47675

Hono: Cookie helper does not sanitize sameSite and priority, allowing Set-Cookie injection

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does not apply the same validation to sameSite and priority. An application that passes user-controlled input into either option may produce a Set-Cookie response header containing attacker-chosen additional attributes. This vulnerability is fixed in 4.12.21.

CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-47676

Hono: app.mount() strips mount prefix using undecoded path, causing incorrect routing for percent-encoded paths

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, app.mount() strips the mount prefix from the incoming request path using the raw URL pathname, while route matching is performed against the percent-decoded path. This inconsistency causes the prefix to be stripped at the wrong position when the path contains percent-encoded multi-byte characters, resulting in the mounted sub-application receiving an incorrect path. This vulnerability is fixed in 4.12.21.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-44457

Hono: Cache Middleware ignores Vary: Authorization / Vary: Cookie leading to cross-user cache leakage

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.18, Cache Middleware does not skip caching for responses that declare per-user variance via Vary: Authorization or Vary: Cookie. As a result, a response cached for one authenticated user may be served to subsequent requests from different users. This vulnerability is fixed in 4.12.18.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-44458

Hono: CSS Declaration Injection via Style Object Values in JSX SSR

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.18, the JSX renderer escapes style attribute object values for HTML but not for CSS. Untrusted input in a style object value or property name can therefore inject additional CSS declarations into the rendered style attribute. The impact is limited to CSS and does not allow JavaScript execution or HTML attribute breakout. This vulnerability is fixed in 4.12.18.

CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-44459

Hono: Improper validation of NumericDate claims (exp, nbf, iat) in JWT verify()

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.18, improper validation of the JWT NumericDate claims exp, nbf, and iat in hono/utils/jwt allows tokens with non-spec-compliant claim values to silently bypass time-based checks. This issue is not exploitable by an anonymous attacker; it only manifests when a malformed claim value reaches verify() — typically when the application itself issues such tokens, or when the signing key is otherwise under attacker control. This vulnerability is fixed in 4.12.18.

CVSS 3.1 · 3.8 Low EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-44455

Hono: Unvalidated JSX Tag Names in hono/jsx May Allow HTML Injection

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.16, Improper handling of JSX element tag names in hono/jsx allowed unvalidated tag names to be directly inserted into the generated HTML output. When untrusted input is used as a tag name via the programmatic jsx() or createElement() APIs during server-side rendering, specially crafted values may break out of the intended element context and inject unintended HTML. This vulnerability is fixed in 4.12.16.

CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-44456

Hono: bodyLimit() can be bypassed for chunked / unknown-length requests

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.16, bodyLimit() does not reliably enforce maxSize for requests without a usable Content-Length (e.g. Transfer-Encoding: chunked). Oversized requests can reach handlers and return 200 instead of 413. This vulnerability is fixed in 4.12.16.

CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-39410

Hono has a non-breaking space prefix bypass in cookie name handling in getCookie()

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a discrepancy between browser cookie parsing and parse() handling allows cookie prefix protections to be bypassed. Cookie names that are treated as distinct by the browser may be normalized to the same key by parse(), allowing attacker-controlled cookies to override legitimate ones. This vulnerability is fixed in 4.12.12.

CVSS 3.1 · 4.8 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono

CVE-2026-39406

@hono/node-server has a middleware bypass via repeated slashes in serveStatic

@hono/node-server allows running the Hono application on Node.js. Prior to 1.19.13, a path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path. When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass. This vulnerability is fixed in 1.19.13.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Node-server

CVE-2026-39407

Hono has a middleware bypass via repeated slashes in serveStatic

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, a path handling inconsistency in serveStatic allows protected static files to be accessed by using repeated slashes (//) in the request path. When route-based middleware (e.g., /admin/*) is used for authorization, the router may not match paths containing repeated slashes, while serveStatic resolves them as normalized paths. This can lead to a middleware bypass. This vulnerability is fixed in 4.12.12.

CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed

Vendors

Hono

Products

Hono