CVE-2026-31854
[cursor] Arbitrary Code Execution via Prompt Injection and Whitelist Bypass
Executive Summary
CVE-2026-31854 is a high severity vulnerability affecting appsec, ai-code. It is classified as OS Command Injection. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"At its core, this issue originates from within ### Summary Cursor, allowing the insecure processing of malicious payloads. This flaw provides a direct pathway for attackers to compromise the entire application stack, rendering traditional defenses ineffective. By intercepting insecure data flows from user input directly to rendering sinks, Precogs is designed to ensure strict authentication requirements are met."
What is this vulnerability?
CVE-2026-31854 is categorized as a critical Application Verification Flaw flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.
Summary Cursor is able to access arbitrary websites. If a visited website contains maliciously crafted instructions, the model may attempt to follow t.
This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.
Risk Assessment
| Metric | Value |
|---|---|
| CVSS Base Score | 8 (HIGH) |
| Vector String | N/A |
| Published | March 9, 2026 |
| Last Modified | March 9, 2026 |
| Related CWEs | CWE-78 |
Impact on Systems
✅ Unauthorized Access: Flaws in application logic can permit unauthorized interaction with protected APIs.
✅ Data Manipulation: Adversaries may alter critical application states, such as user roles or configurations.
✅ Service Disruption: Improper error handling or unvalidated inputs can lead to resource exhaustion.
How to fix this issue?
Implement the following strategic mitigations immediately to eliminate the attack surface.
1. Defense in Depth Implement multi-layered validation (client-side, API gateway, and server-side).
2. Least Privilege Ensure backend service accounts operate with the absolute minimum rights required.
3. Security Regression Testing Integrate automated semantic security scanning into the deployment pipeline.
Vulnerability Signature
// Generic Application Security Flaw (Node.js)
app.post('/api/update-profile', (req, res) =\> \{
// DANGEROUS: Mass Assignment / Object Injection
// Attacker can pass \{ "isAdmin": true, "email": "..." \}
User.update(\{ id: req.user.id \}, req.body);
// SECURED: Explicitly select permitted fields
const \{ email, displayName, bio \} = req.body;
User.update(\{ id: req.user.id \}, \{ email, displayName, bio \});
\});
References and Sources
- NVD — CVE-2026-31854
- MITRE — CVE-2026-31854
- CWE-78 — MITRE CWE
- CWE-78 Details
- Application Security Vulnerabilities
- AI Code Security Vulnerabilities
Vulnerability Code Signature
Attack Data Flow
| Stage | Detail |
|---|---|
| Source | User-supplied system argument |
| Vector | Argument appended to a shell command string |
| Sink | child_process.exec() or similar OS execution sink |
| Impact | Remote Code Execution (RCE), full system compromise |
Vulnerable Code Pattern
// ❌ VULNERABLE: OS command injection
const { exec } = require('child_process');
function pingHost(host) {
// Taint sink: unvalidated host string executed in shell
exec('ping -c 4 ' + host, (error, stdout, stderr) => {
console.log(stdout);
});
}
Secure Code Pattern
// ✅ SECURE: ExecFile with parameter arrays
const { execFile } = require('child_process');
function pingHost(host) {
// Sanitized execution: arguments passed safely, bypassing shell interpolation
execFile('ping', ['-c', '4', host], (error, stdout, stderr) => {
console.log(stdout);
});
}
How Precogs Detects This
Precogs AI Analysis Engine natively intercepts unsafe OS command execution sinks, ensuring all arguments are properly separated from the execution context.\n