The 10 most common vulnerabilities detected during a code audit

SQL injection remains at the top of the list

SQL injection remains one of the most critical and widespread vulnerabilities. It occurs when user data is directly integrated into SQL queries without proper validation or escaping. An attacker can manipulate these queries to access the entire database, modify sensitive information, or even delete entire tables. This flaw is particularly dangerous because it can compromise an entire company's information system in a matter of seconds.

XSS vulnerabilities compromise browsers

Cross-Site Scripting, or XSS, allows an attacker to inject malicious JavaScript code into web pages viewed by other users. This vulnerability occurs when the application displays user content without filtering it properly. The consequences range from session cookie theft to redirection to fraudulent sites and malware installation. High-traffic sites are particularly targeted because a single flaw can affect millions of visitors.

Faulty authentication management

Poorly implemented authentication mechanisms constitute a major breach. We regularly see applications that store passwords in plain text, use obsolete encryption algorithms, or allow unlimited brute force attacks. The lack of robust session validation, predictable tokens, or overly long expiration times also make it easier to take control of legitimate accounts.

The exposure of sensitive data

Many applications unintentionally expose confidential information. This includes credit card numbers transmitted without encryption, publicly accessible configuration files, or overly detailed error messages revealing the internal structure of the system. Developers sometimes forget that sensitive data must be protected not only in transit but also at rest, in databases and backups.

Insufficient access control

Access control flaws allow users to perform actions beyond their legitimate permissions. A standard user can thus access administrative features simply by modifying a URL parameter or identifier in a request. This vulnerability often stems from client-side verification alone, without proper server validation of access rights.

Incorrect security configuration

Unmodified default settings, unnecessary services enabled, or publicly accessible administration pages are common configuration errors. Frameworks and servers are often deployed with permissive configurations intended for development but dangerous in production. Missing HTTP security headers also expose the application to various attacks.

The use of vulnerable components

Outdated third-party libraries and dependencies pose a significant risk. Developers regularly integrate components without checking for known vulnerabilities or keeping their versions up to date. A single compromised library can expose the entire application, as demonstrated by recent vulnerabilities in popular frameworks.

Unsecure deserialization

Deserialization of objects from untrusted sources can lead to arbitrary code execution. This technical vulnerability, although complex to exploit, provides complete control of the server when present. It appears in applications that reconstruct objects from external data without strict validation.

Inadequate logging and monitoring

The absence of detailed logs or their poor configuration prevents the detection of security incidents. Without proper traceability, attacks can go unnoticed for months, allowing intruders to extract data without being detected. Audits frequently reveal that critical events are not recorded or that logs are overwritten too quickly.

Unvalidated redirects

Unvalidated redirects and transfers allow attackers to redirect users to malicious sites by exploiting the trust placed in the legitimate domain. This vulnerability is particularly effective in phishing campaigns because the initial URL appears to come from a trusted source.

Preventing these vulnerabilities requires a comprehensive approach combining developer training, regular code reviews, automated security testing, and external audits. Each vulnerability that is fixed significantly strengthens the application's security posture.