CVE-2024-27936

A maliciously crafted permission request can show the spoofed permission prompt by inserting a broken ANSI escape sequence into the request contents.

Details

In the patch for CVE-2023-28446, Deno is stripping any ANSI escape sequences from the permission prompt, but permissions given to the program are based on the contents that contain the ANSI escape sequences.

For example, requesting the read permission with /tmp/hello\u001b[/../../etc/hosts as a path will display the /tmp/hellotc/hosts in the permission prompt, but the actual permission given to the program is /tmp/hello\u001b[/../../etc/hosts, which is /etc/hosts after the normalization.

This difference allows a malicious Deno program to spoof the contents of the permission prompt.

PoC

Run the following JavaScript and observe that /tmp/hellotc/hosts is displayed in the permission prompt instead of /etc/hosts, although Deno gives access to /etc/hosts.

const permission = { name: "read", path: "/tmp/hello\u001b[/../../etc/hosts" };
await Deno.permissions.request(permission);
console.log(await Deno.readTextFile("/etc/hosts"));

Expected prompt

┌ ⚠️  Deno requests read access to "/etc/hosts".
├ Requested by `Deno.permissions.query()` API
├ Run again with --allow-read to bypass this prompt.
└ Allow? [y/n/A] (y = yes, allow; n = no, deny; A = allow all read permissions) >

Actual prompt

┌ ⚠️  Deno requests read access to "/tmp/hellotc/hosts".
├ Requested by `Deno.permissions.query()` API
├ Run again with --allow-read to bypass this prompt.
└ Allow? [y/n/A] (y = yes, allow; n = no, deny; A = allow all read permissions) >

Any Deno program can spoof the content of the interactive permission prompt by inserting a broken ANSI code, which allows a malicious Deno program to display the wrong file path or program name to the user.

CVE-2024-27936 has a CVSS score of 8.8 (High). The vector is network-reachable, no privileges required, and user interaction required. 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 (1.41.0, 0.147.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-27936? CVE-2024-27936 is a high-severity security vulnerability in deno (rust), affecting versions >= 1.32.1, < 1.41.0. It is fixed in 1.41.0, 0.147.0.
2. How severe is CVE-2024-27936? CVE-2024-27936 has a CVSS score of 8.8 (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 packages are affected by CVE-2024-27936?
   • deno (rust) (versions >= 1.32.1, < 1.41.0)
   • deno_runtime (rust) (versions >= 0.103.0, < 0.147.0)
4. Is there a fix for CVE-2024-27936? Yes. CVE-2024-27936 is fixed in 1.41.0, 0.147.0. Upgrade to this version or later.
5. Is CVE-2024-27936 exploitable, and should I be worried? Whether CVE-2024-27936 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-2024-27936 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-2024-27936?
   • Upgrade deno to 1.41.0 or later
   • Upgrade deno_runtime to 0.147.0 or later