Package Instance

Hono missing validation of cookie name on write path in setCookie()
## Summary

Cookie names are not validated on the write path when using `setCookie()`, `serialize()`, or `serializeSigned()` to generate Set-Cookie headers.

While certain cookie attributes such as domain and path are validated, the cookie name itself may contain invalid characters.

This results in inconsistent handling of cookie names between parsing (read path) and serialization (write path).

## Details

When applications use `setCookie()`, `serialize()`, or `serializeSigned()` with a user-controlled cookie name, invalid values (e.g., containing control characters such as `\r` or `\n`) can be used to construct malformed `Set-Cookie` header values.

For example:

```
Set-Cookie: legit
X-Injected: evil=value
```

However, in modern runtimes such as Node.js and Cloudflare Workers, such invalid header values are rejected and result in a runtime error before the response is sent.

As a result, the reported header injection / response splitting behavior could not be reproduced in these environments.

## Impact

Applications that pass untrusted input as the cookie name to `setCookie()`, `serialize()`, or `serializeSigned()` may encounter runtime errors due to invalid header values.

In tested environments, malformed `Set-Cookie` headers are rejected before being sent, and the reported header injection behavior could not be reproduced.

This issue primarily affects correctness and robustness rather than introducing a confirmed exploitable vulnerability.

hono Improperly Handles JSX Attribute Names Allows HTML Injection in hono/jsx SSR
## Summary

Improper handling of JSX attribute names in hono/jsx allows malformed attribute keys to corrupt the generated HTML output.

When untrusted input is used as attribute keys during server-side rendering, specially crafted keys can break out of attribute or tag boundaries and inject unintended HTML.

## Details

When rendering JSX elements to HTML strings, attribute values are escaped, but attribute names (keys) were previously inserted into the output without validation.

If an attribute name contains characters such as `"`, `>`, or whitespace, it can alter the structure of the generated HTML.

For example, malformed attribute names can:

* Break out of the current attribute and introduce unintended additional attributes
* Break out of the current HTML tag and inject new elements into the output

This issue arises when untrusted input (such as query parameters or form data) is used as JSX attribute keys during server-side rendering.

## Impact

An attacker who can control attribute keys used in JSX rendering may inject unintended attributes or HTML elements into the generated output.

This may lead to:

* Injection of unexpected HTML attributes
* Corruption of the HTML structure
* Potential cross-site scripting (XSS) if combined with unsafe usage patterns

This issue affects applications that pass untrusted input as JSX attribute keys during server-side rendering.