CVE-2026-25050: Vendure Information Disclosure Vulnerability

CVE-2026-25050 Overview

CVE-2026-25050 is a timing attack vulnerability in Vendure, an open-source headless commerce platform. Prior to version 3.5.3, the NativeAuthenticationStrategy.authenticate() method is vulnerable to a timing attack that allows attackers to enumerate valid usernames (email addresses). The vulnerability exists in packages/core/src/config/auth/native-authentication-strategy.ts, where the authenticate method returns immediately if a user is not found, creating a measurable timing difference that can be exploited.

Critical Impact

Attackers can reliably distinguish between existing and non-existing accounts by measuring authentication response times, enabling targeted attacks against confirmed user accounts.

Affected Products

• Vendure versions prior to 3.5.3
• Vendure headless commerce platform (all configurations using NativeAuthenticationStrategy)

Discovery Timeline

• 2026-01-30 - CVE CVE-2026-25050 published to NVD
• 2026-02-04 - Last updated in NVD database

Technical Details for CVE-2026-25050

Vulnerability Analysis

This vulnerability is classified under CWE-202 (Exposure of Sensitive Information Through Data Queries). The core issue lies in the authentication flow's non-constant-time response behavior. When a user attempts to authenticate, the system performs a database lookup to find the user account. If the account exists, the system proceeds to verify the password using bcrypt hashing, which is computationally expensive by design (taking approximately 200-400ms). However, if the user account does not exist, the system returns immediately without performing the bcrypt comparison, resulting in response times of only 1-5ms.

This significant timing differential creates a reliable side-channel that attackers can exploit to determine whether an email address is registered in the system. Such user enumeration capabilities are particularly dangerous for e-commerce platforms where customer account information is sensitive and can be leveraged for targeted phishing campaigns, credential stuffing attacks, or account takeover attempts.

Root Cause

The root cause is the early return pattern in the NativeAuthenticationStrategy.authenticate() method located in packages/core/src/config/auth/native-authentication-strategy.ts. When no user is found during the database lookup, the function returns a failure response immediately, bypassing the computationally expensive bcrypt password comparison. This creates a measurable timing difference between authentication attempts for valid versus invalid usernames.

The proper mitigation requires ensuring constant-time responses regardless of whether the user exists, typically by performing a dummy bcrypt comparison even when the user is not found.

Attack Vector

The attack is network-accessible and requires no authentication or user interaction. An attacker can automate requests to the authentication endpoint with different email addresses and measure response times. By analyzing the timing patterns, the attacker can build a list of valid email addresses registered on the platform.

The attack methodology typically involves:

1. Sending authentication requests with a list of potential email addresses
2. Recording the response time for each request
3. Statistical analysis to identify fast responses (user not found) versus slow responses (user exists, bcrypt executed)
4. Compiling a list of confirmed valid accounts for further attacks

Detection Methods for CVE-2026-25050

Indicators of Compromise

• Unusual volume of failed authentication attempts from single IP addresses or ranges
• Sequential authentication attempts testing different email addresses with similar passwords
• Authentication request patterns showing systematic enumeration behavior
• Logs showing rapid succession of authentication failures with varying usernames

Detection Strategies

• Implement rate limiting on authentication endpoints to slow enumeration attempts
• Monitor for authentication requests with statistically unusual timing patterns
• Alert on high volumes of failed authentication attempts from single sources
• Deploy web application firewall (WAF) rules to detect enumeration patterns
• Analyze authentication logs for sequential email address testing patterns

Monitoring Recommendations

• Enable detailed logging for all authentication attempts including timestamps and response times
• Set up alerts for authentication failure rates exceeding baseline thresholds
• Monitor for automated traffic patterns targeting the authentication endpoint
• Implement anomaly detection on login attempt frequency per IP address

How to Mitigate CVE-2026-25050

Immediate Actions Required

• Upgrade Vendure to version 3.5.3 or later immediately
• Review authentication logs for signs of prior enumeration attempts
• Implement rate limiting on authentication endpoints if not already in place
• Consider implementing CAPTCHA for authentication flows to prevent automated attacks

Patch Information

Vendure version 3.5.3 includes a fix for this timing attack vulnerability. The patch ensures constant-time responses in the authentication flow regardless of whether the user account exists. Organizations should upgrade to this version or later to remediate the vulnerability.

For detailed information about the fix, refer to the GitHub Vendure Release v3.5.3 and the GitHub Security Advisory GHSA-6f65-4fv2-wwch.

Workarounds

• Implement rate limiting at the network or application level to slow enumeration attempts
• Add artificial delays to authentication responses to normalize timing differences
• Deploy a Web Application Firewall (WAF) with rules to detect and block enumeration patterns
• Consider implementing account lockout policies after multiple failed attempts
• Use CAPTCHA challenges after initial authentication failures to prevent automation

# Example: Add rate limiting with nginx
# Add to nginx configuration for authentication endpoint
location /api/authenticate {
    limit_req zone=auth_limit burst=5 nodelay;
    limit_req_status 429;
    proxy_pass http://vendure_backend;
}