Top 5 Computer Vulnerabilities: How to Fix Them, Best Practices & Compliance Tips

You face a small set of recurring weaknesses that cause a large share of breaches. This guide explains the top 5 computer vulnerabilities and shows you how to fix them with practical steps, best practices, vulnerability patch management, and OWASP Top Ten compliance considerations.

Across all sections, prioritize input validation controls, secure defaults, and least privilege. Where possible, replace brittle patterns with safer frameworks or managed services, and enforce repeatable build, test, and deploy pipelines.

Cross-Site Scripting Vulnerabilities

What it is and why it matters

Cross-Site Scripting (XSS) lets attackers run scripts in a user’s browser, stealing sessions, defacing pages, or pivoting into internal apps. It persists because browsers faithfully execute injected HTML/JS unless you deliberately constrain them.

How it happens

• Reflected: unsanitized input is echoed in a response and executed when a user clicks a crafted link.
• Stored: malicious script is saved in a database or CMS and delivered to many users.
• DOM-based: client-side JavaScript reads unsanitized input and writes it back to the DOM.

How to fix it

• Encode on output: treat all dynamic content as untrusted; use context-aware escaping (HTML, attribute, JS, URL) in templates.
• Apply input validation controls: allowlist expected formats (e.g., email, UUID, numeric ranges) and reject everything else.
• Adopt frameworks with auto-escaping and avoid string concatenation for HTML.
• Enable Content Security Policy (CSP) to block inline scripts and restrict sources; set HttpOnly and Secure on cookies.
• Sanitize rich text using a vetted HTML sanitizer with an explicit allowlist of tags and attributes.

Best practices and compliance tips

• Centralize encoding and sanitization utilities; ban unsafe sinks in code review and static analysis.
• Practice vulnerability patch management for front-end libraries and plugins; remove abandoned dependencies.
• Map controls to OWASP Top Ten compliance by documenting your XSS prevention policy, threat model, and test coverage.

Managing Out-of-Bounds Write Issues

What it is and why it matters

Out-of-bounds writes corrupt memory adjacent to a buffer, enabling crashes, data corruption, or arbitrary code execution. They often arise in C/C++ code that manipulates raw pointers or unsafe APIs.

Common root causes

• Trusting user-controlled lengths or indexes without bounds checks.
• Using deprecated or unsafe functions (e.g., gets, strcpy, sprintf) and manual memory management.
• Integer overflows during size calculations leading to undersized allocations.

How to detect it

• Fuzzing with coverage guidance to explore edge cases and malformed inputs.
• Sanitizers and runtime tooling (ASan/UBSan, Valgrind) in CI to surface memory errors early.
• Static analysis to flag risky patterns and tainted-size arithmetic.

How to fix it

• Prefer memory-safe languages or components where feasible; otherwise wrap unsafe code behind safe interfaces.
• Use size-aware APIs and explicit bounds checks on every index and copy.
• Adopt canaries, DEP, and ASLR; compile with hardened flags and enable stack protection.
• Implement rigorous memory corruption prevention with code reviews focused on pointer arithmetic and lifetime rules.

// Vulnerable
void copy(char *dst, const char *src, size_t len) {
    for (size_t i = 0; i < len; i++) dst[i] = src[i]; // len may exceed dst size
}

// Safer
int copy_bounded(char *dst, size_t dst_sz, const char *src, size_t len) {
    if (len >= dst_sz) return -1;               // reject or truncate
    memcpy(dst, src, len);
    dst[len] = '\0';
    return 0;
}

Best practices and compliance tips

• Maintain a banned-APIs list; enforce with linters and pre-commit hooks.
• Integrate fuzzing and sanitizers into nightly builds; track coverage and crash triage.
• Treat fixes as part of vulnerability patch management with clear SLAs and regression tests.
• Document processes to support OWASP Top Ten compliance, especially for memory safety in native modules.

Preventing SQL Injection Attacks

What it is and why it matters

SQL injection occurs when untrusted input alters a database query, enabling data theft, tampering, or authentication bypass. It is preventable with parameterized queries and disciplined access control.

How to detect it

• SAST rules for string-built queries and concatenated WHERE clauses.
• DAST scanners and unit tests that try classic payloads and boundary cases.
• Database logs for anomalous statements and unexpected errors (e.g., syntax errors with quotes).

How to fix it

• Use parameterized queries or prepared statements everywhere; never concatenate user input into SQL.
• For dynamic identifiers (e.g., ORDER BY), use allowlists and map tokens to safe values.
• Enforce least-privilege database accounts; separate read and write roles.
• Combine with input validation controls to constrain formats and lengths.

# Python (psycopg2)
cur.execute("SELECT * FROM users WHERE email = %s", (email,))

// Node.js (mysql2)
const [rows] = await db.execute("UPDATE posts SET title=? WHERE id=?", [title, id]);

Best practices and compliance tips

• Adopt an ORM that emits parameterized queries by default; ban raw SQL unless reviewed.
• Rotate credentials and store secrets securely; monitor for anomalous query patterns.
• Record your standardized query patterns to demonstrate OWASP Top Ten compliance.
• Include database engine patches in your vulnerability patch management plan.

Mitigating Cross-Site Request Forgery

What it is and why it matters

CSRF tricks an authenticated user’s browser into sending state-changing requests to your app. Without defenses, attackers can transfer funds, change emails, or escalate privileges silently.

How to detect it

• Inventory state-changing endpoints; ensure none accept GET and all require strong protections.
• Check for anti-CSRF tokens, Origin/Referer validation, and SameSite cookies in requests.
• Use automated tests that attempt cross-origin form submissions and script-based requests.

How to fix it

• Implement anti-CSRF tokens (synchronizer tokens or double-submit cookies) and rotate them per session or request.
• Set SameSite=Lax or Strict on session cookies; mark them HttpOnly and Secure.
• Validate Origin and Referer on risky operations; block cross-origin state changes.
• Require re-authentication or step-up verification for high-value actions.

// Pseudocode
if (!validCsrfToken(request.token, session.id)) reject(403);
if (!isTrustedOrigin(request.headers.Origin)) reject(403);

Best practices and compliance tips

• Disallow CSRF on GET; design APIs to be idempotent and safe for caching.
• Document token issuance and validation flows to support OWASP Top Ten compliance.
• Include cookie settings and token libraries in vulnerability patch management.

Securing Against Command Injection

What it is and why it matters

Command injection happens when user input influences a shell command or interpreter call. Attackers can execute arbitrary commands, exfiltrate data, or move laterally.

How to detect it

• Search code for shell, exec, process, or eval APIs that accept user input.
• Fuzz parameters that flow into system commands; monitor for unexpected subprocess behavior.
• Use static analysis to trace tainted input reaching command execution sinks.

How to fix it

• Apply command execution restriction: avoid shells; call specific binaries via safe APIs with arguments separated.
• Use strict allowlists for commands, flags, and file paths; reject everything else.
• Escape only as a last resort; prefer structured parameters and library calls.
• Run with least privilege, apply seccomp/AppArmor or containers, and set timeouts.

# Python
subprocess.run(["/usr/bin/convert", src, "-resize", "640x480", dst], check=True)

// Node.js
child_process.execFile("/usr/bin/ffprobe", ["-v", "error", "-show_format", file], (e) => { /* ... */ })

Best practices and compliance tips

• Combine input validation controls with centralized wrappers around subprocess calls.
• Log command invocations and outcomes; alert on forbidden arguments or destinations.
• Track CLI tool updates as part of vulnerability patch management; remove unused tools.
• Document safe-command policies to demonstrate OWASP Top Ten compliance.

Conclusion

These five areas—XSS, out-of-bounds writes, SQL injection, CSRF, and command injection—account for much of today’s risk. Standardize secure coding patterns, enforce parameterization and allowlists, harden memory handling, and formalize vulnerability patch management to sustain OWASP Top Ten compliance over time.

FAQs.

What are the top computer vulnerabilities to address?

The most impactful set includes Cross-Site Scripting, out-of-bounds write memory errors, SQL injection, Cross-Site Request Forgery, and command injection. Focusing on these with strong input validation controls, least privilege, and routine patching reduces real-world incident likelihood significantly.

How can organizations comply with security best practices?

Define secure coding standards, mandate parameterized queries and output encoding, adopt anti-CSRF tokens, and enforce command execution restriction. Back policies with automated tests, SAST/DAST, and vulnerability patch management, and map evidence to OWASP Top Ten compliance for governance.

What methods effectively prevent SQL injection?

Use parameterized queries or prepared statements everywhere; add allowlists for dynamic identifiers, enforce least-privilege DB roles, and validate inputs. Monitor logs for anomalous queries and keep database engines and drivers patched.

How to detect and fix out-of-bounds write errors?

Combine fuzzing, sanitizers (ASan/UBSan), and static analysis to reveal memory writes past buffer boundaries. Fix by adding bounds checks, using size-aware APIs, avoiding unsafe functions, and adopting memory-safe components where practical as part of a comprehensive memory corruption prevention strategy.