CVE-2026-27977
Next.
Executive Summary
CVE-2026-27977 is a medium severity vulnerability affecting pii-secrets. It is classified as CWE-1385. Ensure your systems and dependencies are patched immediately to mitigate exposure risks.
Precogs AI Insight
"This critical flaw stems from within Next.js, allowing the improper handling of untrusted input. In a real-world scenario, an attacker could exploit this by silently exfiltrate sensitive routing topologies and internal schemas. Precogs automatically detects reversible cryptographic functions and hardcoded secrets to block malicious interactions before they reach production."
What is this vulnerability?
CVE-2026-27977 is categorized as a critical Cross-Site Scripting (XSS) flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.
Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in next dev, cross-site pr...
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 | 5.4 (MEDIUM) |
| Vector String | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N |
| Published | March 18, 2026 |
| Last Modified | March 18, 2026 |
| Related CWEs | CWE-1385 |
Impact on Systems
✅ Session Hijacking: Attackers can steal active user session tokens (cookies) to impersonate the victim.
✅ Phishing Execution: Malicious scripts can dynamically alter DOM content to present fraudulent login forms.
✅ Worm Propagation: Stored XSS can spread autonomously as users visit the infected page.
How to fix this issue?
Implement the following strategic mitigations immediately to eliminate the attack surface.
1. Output Encoding Implement strict context-aware output encoding (HTML, JavaScript, Attribute, CSS) before rendering user data.
2. Content Security Policy (CSP) Deploy a rigorous CSP header to restrict script execution exclusively to trusted domains.
3. Framework Defenses Utilize native UI framework protections (e.g., React DOM escaping) and avoid dangerouslySetInnerHTML.
Vulnerability Signature
// Example DOM-based XSS vulnerability
const user_input = new URLSearchParams(window.location.search).get('q');
// VULNERABLE: Direct insertion into innerHTML
document.getElementById('results').innerHTML = "Results for: " + user_input;
// EXPLOIT PAYLOAD: ?q=\<img src=x onerror=alert(document.cookie)\>
References and Sources
- NVD — CVE-2026-27977
- MITRE — CVE-2026-27977
- CWE-1385 — MITRE CWE
- CWE-1385 Details
- PII and Secrets Exposure
Vulnerability Code Signature
Attack Data Flow
| Stage | Detail |
|---|---|
| Source | Source code repository or API response |
| Vector | Secrets embedded directly in the codebase or PII leaked in response |
| Sink | Version control system or HTTP response |
| Impact | Data breach, unauthorized access, compliance violation |
Vulnerable Code Pattern
// ❌ VULNERABLE: Hardcoded credential & PII Leak
public class Config {
// Taint sink: secret embedded in code
public static final String API_KEY = "sk_live_1234567890abcdef";
}
// ... API Response leaks full user details including SSN ...
Secure Code Pattern
// ✅ SECURE: Environment variables & Data Masking
public class Config {
// Sanitized configuration
public static final String API_KEY = System.getenv("STRIPE_API_KEY");
}
// ... API Response masks SSN and restricts PII exposure ...
How Precogs Detects This
Precogs PII & Secrets Scanner continuously monitors codebases and API responses for hardcoded secrets and unintended PII exposure.\n