CVE-2024-27931

Insufficient permission checking in Deno.makeTemp* APIs

Insufficient validation of parameters in Deno.makeTemp* APIs would allow for creation of files outside of the allowed directories. This may allow the user to overwrite important files on the system that may affect other systems.

A user may provide a prefix or suffix to a Deno.makeTemp* API containing path traversal characters. The permission check would prompt for the base directory of the API, but the final file that was created would be outside of this directory:

$ mkdir /tmp/good
$ mkdir /tmp/bad
$ deno repl --allow-write=/tmp/good
> Deno.makeTempFileSync({ dir: "/tmp/bad" })
┌ ⚠️  Deno requests write access to "/tmp/bad".
├ Requested by `Deno.makeTempFile()` API.
├ Run again with --allow-write to bypass this prompt.
└ Allow? [y/n/A] (y = yes, allow; n = no, deny; A = allow all write permissions) > n
❌ Denied write access to "/tmp/bad".
Uncaught PermissionDenied: Requires write access to "/tmp/bad", run again with the --allow-write flag
    at Object.makeTempFileSync (ext:deno_fs/30_fs.js:176:10)
    at <anonymous>:1:27
> Deno.makeTempFileSync({ dir: "/tmp/good", prefix: "../bad/" })
"/tmp/good/../bad/a9432ef5"
$ ls -l /tmp/bad/a9432ef5
-rw-------@ 1 user  group  0 Mar  4 09:20 /tmp/bad/a9432ef5

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2024-27931 has a CVSS score of 5.8 (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 (1.41.1); upgrading removes the vulnerable code path.

Kodem intelligence

This is fixed in Deno 1.41.1.

1. What is CVE-2024-27931? CVE-2024-27931 is a medium-severity improper input validation vulnerability in deno (rust), affecting versions < 1.41.1. It is fixed in 1.41.1. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2024-27931? CVE-2024-27931 has a CVSS score of 5.8 (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-2024-27931? deno (rust) versions < 1.41.1 is affected.
4. Is there a fix for CVE-2024-27931? Yes. CVE-2024-27931 is fixed in 1.41.1. Upgrade to this version or later.
5. Is CVE-2024-27931 exploitable, and should I be worried? Whether CVE-2024-27931 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-2024-27931 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-2024-27931? Upgrade deno to 1.41.1 or later.

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