CVE-2025-54135

[cursor] Arbitrary code execution from Cursor Agent through a prompt injection via MCP Special Files

Verified by Precogs Threat Research
Last Updated: Aug 2, 2025
Base Score
8HIGH

Executive Summary

CVE-2025-54135 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

"The underlying mechanism of this vulnerability involves within ## Summary Cursor, allowing a failure to enforce strict data boundary conditions. A threat actor could leverage this oversight to gain unauthorized read or write access, effectively hijacking underlying configurations. Precogs identifies insecure data flow paths before deployment to safeguard the application against payload injection."

Exploit Probability (EPSS)
Low (0.1%)
Public POC
Undisclosed
Exploit Probability
Elevated (52%)
Public POC
Available
Affected Assets
appsecai codeCWE-78

What is this vulnerability?

CVE-2025-54135 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 allows writing in-workspace files with no user approval. If the file is a dotfile, editing it requires approval but creating one if it d.

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

MetricValue
CVSS Base Score8 (HIGH)
Vector StringN/A
PublishedAugust 2, 2025
Last ModifiedAugust 2, 2025
Related CWEsCWE-78, CWE-829

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

Vulnerability Code Signature

Attack Data Flow

StageDetail
SourceUser-supplied system argument
VectorArgument appended to a shell command string
Sinkchild_process.exec() or similar OS execution sink
ImpactRemote 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

Related Vulnerabilitiesvia CWE-78

Is your system affected?

Precogs AI detects CVE-2025-54135 in compiled binaries, LLMs, and application layers — even without source code access.