CVE-2024-27931 — deno
MEDIUMCVE-2024-27931 is a medium-severity (CVSS 5.8) Improper Input Validation vulnerability in deno. 1 public exploit reference exists, 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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-27931 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Research 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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-27931 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-27931. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-27931 in your dependencies?
O3 Security finds CVE-2024-27931 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.