May 28th, 2026, posted in for_founders
by Adelina
When working on a software product, most times you just want it to launch. No matter what, it’s gotta work and be ready to reach customers.
And in this whirlwind, you might neglect software security. After all, you’re trying to launch fast and get your investment back, right? Well, think again.
Security issues don't wait around for a convenient time to show up. They get exploited. And when they do, the fallout (a data breach, a regulatory fine, a loss of user trust) can do more damage to your business than missing a product deadline ever would.
In this article, we’re going to give you a practical understanding of what security vulnerabilities actually are, how they put your app at risk, and most importantly what you can do about them right now.
What are software security fixes, and why you need to care about them
Before we get into the list, let's talk about what a "security fix" actually means in the context of software development.
Think of your app like a house. You've designed it carefully, furnished it, and invited people to live in it. But if you left a window unlocked on the second floor, a door with a broken latch, or a spare key under the doormat, a determined intruder could find their way in regardless of how well-designed everything else is.
Security vulnerabilities in software work the same way: they're the unlocked windows and broken latches that attackers can exploit.
A security fix, then, is anything you do to close those gaps. It could be a code change, a configuration update, a library patch, or an architectural adjustment. What all security fixes have in common is that they eliminate a specific weakness before it can be turned against you.
The two main categories you need to worry about are:
- Exploitable vulnerabilities a.k.a technical weaknesses: things like outdated dependencies with known security holes, misconfigured servers, or code that doesn't properly sanitize user input. These are the kinds of issues that show up in databases like the National Vulnerability Database, and attackers often have automated tools to scan for them at scale.
- Logic flaws, which are trickier. They're not bugs in the traditional sense, as the code works the way it’s supposed to. The problem is that the *logic* itself is flawed, and a clever user can exploit that. Imagine an e-commerce app where a discount code can be applied multiple times because nothing in the code checks for that. The code runs fine. The business bleeds money.
Both types of vulnerabilities can lead to data breaches, unauthorized access, financial loss, and reputational damage. And both require deliberate, ongoing attention to prevent.
So up next, we’re going to list seven security fixes that deserve a place on your team's roadmap. Not next quarter, but now.
Fix 1: Implement proper input validation and sanitization
One of the oldest tricks in the attacker's playbook is injecting malicious content through inputs in your app. SQL injection, cross-site scripting (XSS), and command injection attacks all hinge on the same idea: if you let users submit arbitrary data and your app trusts it blindly, attackers can send malicious payloads instead of legitimate inputs.
The app processes the payload, and suddenly you've handed someone the keys to your database or your users' browsers.
Input validation means checking that the data submitted by a user conforms to what your app actually expects. A phone number field should only accept numbers in the right format. A name field shouldn't accept JavaScript. An ID parameter in a URL shouldn't accept anything other than a valid identifier. The goal is to reject anything that doesn't belong before it ever reaches your business logic or your database.
Sanitization goes one step further: it means cleaning or escaping data that will be rendered or executed somewhere. Even if a user manages to submit something unexpected, sanitization ensures it doesn't get interpreted as code.
Parameterized queries in database operations are a classic example: instead of building a SQL query by concatenating user input as a string (dangerous), you pass user input as a parameter that the database engine treats as data, not as instructions.
The common mistake teams make here is treating validation as a one-time checkbox rather than a discipline. You need to validate and sanitize on the server side, not just the client side, because client-side checks are trivially bypassed.
You also need to think about every input surface: forms, API endpoints, URL parameters, file uploads, even HTTP headers. An attacker will find the one input you forgot about.
Fix 2: Strong authentication and session management
Weak authentication is one of the most common causes of unauthorized access, and it's also one of the most avoidable. If your app lets users authenticate with weak passwords, doesn't enforce multi-factor authentication (MFA) for sensitive operations, or mismanages session tokens, you're leaving an enormous attack surface open.
Think of session management like the wristband system at a concert. You prove who you are at the door, you get a wristband, and from that point on, staff check your wristband rather than asking for your ID every time.
The problem is if those wristbands are easy to forge, never expire, or don't get revoked when they should. Session tokens work the same way: they're how your app recognizes a returning authenticated user. If those tokens are predictable, too long-lived, or transmitted insecurely, attackers can steal or forge them.
On the authentication side, enforce minimum password complexity requirements, store passwords using modern hashing algorithms like bcrypt or Argon2 (never plain text or MD5), and implement rate limiting on login attempts to prevent brute force attacks.
For any operation touching sensitive data or settings, MFA adds an essential second layer of verification that a stolen password alone can't defeat.
On the session management side, generate session tokens with sufficient entropy so they can't be guessed, set them to expire after a reasonable period of inactivity, invalidate them on logout, and rotate them on privilege escalation.
Transmit them only over HTTPS, and use the Secure and HttpOnly flags on cookies to prevent them from being accessed by JavaScript or sent over unencrypted connections. These are not extreme measures: they're baseline strategies that every app handling user data should have in place.
Fix 3: Apply the principle of least privilege
The principle of least privilege is simple: every user, process, and service in your system should have access only to what it actually needs to do its job, and nothing more. We've talked about this in a previous article about whether you're exposing your internal security.
It sounds obvious in theory, but in practice, teams frequently grant broad permissions out of convenience or expediency, and those over-permissioned accounts become liabilities.
Imagine your app's database user has admin-level privileges because it was easier to set up that way during development. Now imagine an attacker exploits an injection vulnerability and gets access to that database connection.
With least privilege in place, they can only access the specific tables your app uses, and only with the specific permissions your app needs. Without it, they have full administrative control over your entire database. The injection vulnerability was the entry point, but over-permissioning determined the blast radius.
This principle applies at every layer. Your app's service accounts should only have access to the specific resources they need. Your API endpoints should verify not just that a user is authenticated, but that they're authorized to perform the specific action they're requesting.
Internal services shouldn't be able to call each other without verification. Admin functions should be locked behind additional checks, not just a Boolean flag in the user table.
Apply the same thinking to your infrastructure. Cloud IAM roles, database accounts, API keys, and third-party integrations all deserve regular audits to ensure they haven't accumulated permissions that were granted "just in case." The more you limit what each component can do, the smaller the damage if any one component is compromised.
Fix 4: Keep dependencies up to date and audit them regularly
Modern apps are built on a stack of dependencies: libraries, frameworks, and third-party packages that do heavy lifting so your team doesn't have to reinvent the wheel. That's a massive productivity win. It's also a massive risk surface if those dependencies aren't maintained.
The Log4Shell vulnerability in 2021 is a memorable example. A flaw in Log4j, an extremely widely used Java logging library, allowed attackers to execute arbitrary code on affected servers.
The library had been included as a dependency in thousands of apps, many of which hadn't been explicitly evaluated for security. Suddenly, teams everywhere were scrambling to figure out whether they were exposed, not because of anything they'd written, but because of a library they'd included.
The fix here has several parts:
- First, use a software composition analysis (SCA) tool: tools like Snyk, Dependabot, or OWASP Dependency-Check can automatically flag dependencies with known vulnerabilities.
- Second, establish a policy for how quickly your team addresses dependency vulnerabilities based on severity. A critical vulnerability in a library that handles authentication deserves immediate attention; a low-severity issue in a dev-only tool can be scheduled for the next sprint.
- Third, minimize your dependency footprint: every library you include is a potential attack surface, so only include what you genuinely need and audit your dependency tree periodically to prune what's no longer used.
It's also worth paying attention to transitive dependencies: the dependencies of your dependencies. These are easy to overlook but can be just as dangerous. Good SCA tooling will surface these for you.
Fix 5: Use HTTPS everywhere and secure your data in transit
If your app is still serving any traffic over HTTP (or if you're assuming TLS is handled somewhere upstream without verifying it) stop reading and fix that first.
Transmitting data over unencrypted connections means anyone on the same network can intercept it. This includes login credentials, session tokens, sensitive user data, and API responses.
TLS (the protocol behind HTTPS) encrypts the connection between a client and a server so that even if traffic is intercepted, it can't be read or tampered with.
Getting TLS set up is no longer the burden it used to be: services like Let's Encrypt provide free, automatically renewing certificates, and modern hosting platforms handle much of the configuration automatically.
But getting TLS in place is just the beginning. You also need to configure it correctly. Use modern protocol versions: TLS 1.2 at minimum, with TLS 1.3 preferred. Avoid weak cipher suites, which are older encryption algorithms with known weaknesses that attackers can exploit even against an encrypted connection.
Use HTTP Strict Transport Security (HSTS) headers to tell browsers to always use HTTPS when accessing your domain, even if a user types the URL without the https:// prefix.
Don't forget internal traffic either. Communication between your app's internal services (microservices, databases, caches, message queues) also deserves encryption. It's easy to assume your internal network is safe, but a compromised component inside your perimeter can move laterally and intercept unencrypted internal traffic.
Fix 6: Implement proper error handling and logging
This one might seem less intuitive as a security fix, but the way your app handles errors can directly determine how much information you hand to attackers: and how quickly you catch a breach when it happens.
On the error handling side
When something goes wrong in your app, users should see a clean, generic error message. What they should not see is a stack trace, a database error message, a file path, or anything else that reveals the internals of your system.
Attackers actively probe apps with malformed inputs specifically to trigger error messages that expose information: what database you're using, what version, what your file structure looks like, which users exist.
Each of those details helps them refine their attack. Detailed error messages are helpful for developers during development; they're a liability in production.
On the logging side
Comprehensive logs are your primary tool for understanding what's happening in your system, catching suspicious behavior early, and reconstructing what happened after an incident.
You want to log authentication events: successful and failed logins, password resets, MFA challenges. You want to log access to sensitive data. You want to log unusual patterns: a user hitting dozens of API endpoints in rapid succession, or repeated failed authorization checks on resources they don't own.
The tricky balance is logging enough to be useful without logging sensitive data itself. Passwords, credit card numbers, and other personally identifiable information should never appear in logs: both for security reasons and for regulatory compliance under frameworks like GDPR and HIPAA.
Structured logging with consistent formats makes logs far easier to query and alert on, especially when you're storing them in a centralized logging system.
Fix 7: Conduct regular security testing and code reviews
All of the fixes above help close known categories of vulnerabilities, but determined attackers are creative, and the threat landscape evolves. The only way to stay ahead is to actively test your app's security rather than assuming it's fine because no one has found a problem yet.
Security testing takes several forms.
- Static Application Security Testing (SAST) tools analyze your source code for known vulnerability patterns without running the app: think of it as a specialized linter for security issues.
- Dynamic Application Security Testing (DAST) tools interact with your running app to find vulnerabilities that only surface at runtime, like improperly secured API endpoints or authentication bypasses. These tools can be integrated into your CI/CD pipeline to catch issues before they reach production.
Penetration testing goes further still. This involves having skilled security professionals (either from your team or from an external firm) deliberately attempt to compromise your app the way a real attacker would.
Pen tests surface vulnerabilities that automated tools miss, especially logic flaws that require human creativity to identify. A good penetration test helps you understand how different vulnerabilities chain together to create realistic attack paths.
Security-focused code reviews are another essential practice. When developers review each other's code, security issues should be as much on the checklist as functional correctness.
This requires either security training for your development team (so they know what to look for) or involvement from someone with dedicated security expertise. The earlier security considerations enter the development process, the cheaper they are to fix.
A vulnerability caught in code review costs a fraction of what it costs to patch in production, and a fraction of a fraction of what it costs when exploited.
Security isn't a project you complete. It's a practice you maintain. The seven fixes above won't make your app invulnerable (nothing will) but they will dramatically reduce your attack surface and make your app a much harder target.
Security debt compounds just like technical debt. Every week you defer input validation, every sprint you skip the dependency audit, every quarter you put off penetration testing is another week, sprint, and quarter that known vulnerabilities remain open. The cost of addressing them grows. The window of exposure widens.
The good news is that most of these fixes aren't difficult or expensive. They're engineering disciplines that, once built into your development process, become routine. The first few sprints you invest in them will pay dividends for as long as your app runs.
If you're not sure where to start, or if your team doesn't have the security expertise to implement these fixes confidently, that's a solvable problem too. We help companies build software that lasts, and we’re here to help you as well. Let’s chat and see what we can work out together.
