CVE-2023-50710: Hono's named path parameters can be overridden in TrieRouter

Impact

The clients may override named path parameter values from previous requests if the application is using TrieRouter. So, there is a risk that a privileged user may use unintended parameters when deleting REST API resources.

TrieRouter is used either explicitly or when the application matches a pattern that is not supported by the default RegExpRouter.

The code to reproduce it. The server side application:

ts import { Hono } from 'hono' import { TrieRouter } from 'hono/router/trie-router'

const wait = async (ms: number) => { return new Promise((resolve) => { setTimeout(resolve, ms) }) }

const app = new Hono({ router: new TrieRouter() })

app.use('', async (c, next) => { await wait(Math.random() 200) return next() })

app.get('/modules/:id/versions/:version', async (c) => { const id = c.req.param('id') const version = c.req.param('version')

console.log('path', c.req.path) console.log('version', version)

return c.json({ id, version, }) })

export default app

The client code which makes requests to the server application:

ts const examples = [ 'http://localhost:8787/modules/first/versions/first', 'http://localhost:8787/modules/second/versions/second', 'http://localhost:8787/modules/third/versions/third', ]

const test = () => { for (const example of examples) { fetch(example) .then((response) => response.json()) .then((data) => { const splitted = example.split('/') const expected = splitted[splitted.length - 1]

if (expected !== data.version) { console.error(Error: exprected ${expected} but got ${data.version} - url was ${example}) } }) } }

test()

The results:

txt Error: exprected second but got third - url was http://localhost:8787/modules/second/versions/second Error: exprected first but got third - url was http://localhost:8787/modules/first/versions/first

Patches

"v3.11.7" includes the change to fix this issue.

Workarounds

Don't use TrieRouter directly.

ts // DON'T USE TrieRouter import { TrieRouter } from 'hono/router/trie-router' const app = new Hono({ router: new TrieRouter() })

References

Router options on the Hono website: https://hono.dev/api/hono#router-option