CVE-2024-27931 — deno
MEDIUMCVE-2024-27931 is a medium-severity (CVSS 5.8) Improper Input Validation vulnerability in deno. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for deno — see the affected versions and patch details below.
Insufficient permission checking in `Deno.makeTemp*` APIs
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-27931.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
denoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Impact
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
Patches
This is fixed in Deno 1.41.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 1.41.1cargo update -p deno --precise 1.41.1 |
Affected Products
denodenoResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for deno, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update deno to 1.41.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27931 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
Frequently Asked Questions
Is CVE-2024-27931 in your dependencies?
Find it across crates.io, including transitive dependencies.