API keys often give a false sense of security: it seems like they protect access to APIs. Yet, there are plenty of API key security risks. For one, they’re simply static strings that are often exposed, leaked, and end up helping attackers. As such, leaky API keys are at the heart of many of today’s high-profile API breaches and data leaks.

The modern API landscape spans microservices and software-as-a-service (SaaS) integrations, and it’s getting a big boost from AI agents. Many of these components are integrated with APIs, meaning the potential attack surface is expanding. And leaky API keys that provide over-permissioned access to such platforms can lead to vulnerabilities and risks like data overexposure, DDoS attacks, cryptojacking, and more — all under the guise of “authenticated” API calls.

Below, we’ll explore ten security issues with API keys that developers may not be aware of at first impression. As we’ll see, they’re not sufficient for authentication and authorization. At best, they’re a simple and easy way to access APIs. At worst, they introduce a systemic weakness to the modern interconnected enterprise, and AI can amplify this gap. It’ll take standards-based API access control to curtail these threats and provide more scoped access.

1. API Keys Are Easily Reused

From a usability point of view, API keys are incredibly easy to generate, store, and reuse to access APIs. However, that same ease of use is great for hackers too. API keys are essentially just a static string credential without a timestamp or proof-of-possession mechanism to validate ownership. Therefore, if an attacker can intercept an API key, they can easily reuse it for malicious purposes. This makes API keys incredibly vulnerable to replay attacks.

2. API Keys Aren’t Safely Stored

API keys are often not stored or handled in a safe manner. Developers often pass keys in headers or query parameters when accessing APIs. Teams often reuse them across environments or share them with each other informally. And while many developers store these credentials as environment variables, they may not always provide sufficient controls. You often still see API keys logged in plaintext in proxies, analytics tools, or left in error logs. Such unsafe practices can threaten the security of API keys.

3. API Keys Are Often Leaked

Since there aren’t always strong storage practices with API keys, they are often leaked. Incredibly, Escape found 18,000 API keys exposed on the public web in 2024. Keys are often accidentally exposed, such as within public GitHub repositories or other projects shared with colleagues or partners. But it’s not always end-developer negligence — API keys can also be stolen during data breaches. Take the recent Vercel breach, in which customer credentials and API keys were exposed due to a compromised third-party SaaS tool. Since API keys are commonly exposed, they’re easy to steal and reuse for malicious purposes.

4. API Keys Are Long-Lived

API keys are typically designed to be used by a client for an extended period of time. As such, they’re typically long-lived or indefinitely applied without any form of session duration. This means that if an attacker exploits a key, they could theoretically use it months later, making traceability to the initial attack nearly impossible. Without built-in expiration or time constraints, static keys aren’t well aligned with least privilege, either, especially if corporate policies shift over time.

5. API Keys Rarely Get Cycled

It’s good security hygiene to reset your passwords, credentials, and access tokens every so often. But API keys often get hardcoded into integrations, making cycling them challenging since changes would incur breaking changes and potentially cascading failures. This results in persistent access with the same key. This is potentially dangerous, as it can lead to shadow integrations with less oversight. And since keys remain hardcoded for a longer period of time, it provides hackers more time to extract and take advantage of them.

6. Disaster Response Is Difficult With API Keys

When a data breach does occur and a system credential is compromised, the only option is to revoke the API key. But similar to the issue with cycling, this isn’t ideal, since it can break any integrations that are dependent upon the key all at once and cause downtime across multiple services. The side effects can discourage teams from rotating keys or even revoking compromised keys proactively. If all you have are records tied to generic API keys, audit trails are weak too, making it hard to trace who exactly made the call.

7. API Keys Are Usually Over-Permissioned

It’s not uncommon for a SaaS service or infrastructure platform to issue an API key to access all methods and operations. However, this can lead to data overexposure and permission sprawl. Static keys don’t allow for fine-grained permissions that match the requester’s role, making them unfit for authorization. They also don’t trigger “step-up” authentication on their own, such as requiring additional authentication factors for suspicious attempts. When used as a wholesale replacement for identity and access management, API keys can grant more privileges than necessary, breaking a zero-trust approach.

8. API Keys Miss Key Identity Context

When using API keys alone, you miss other important signals that paint a picture of the identity of the requesting party. These cues include time-based controls, geography, IP address, and other conditions. API keys are typically just a single static string and typically represent a project or an account, not a specific end user. They don’t convey identity information, let alone specific roles or permissions, which could help properly inform an access decision. Without identity context, systems accept requests somewhat blindly, which is cause for concern given 95% of API attacks originate from authenticated sources, according to research from Salt Security.

9. AI Agents Exacerbate API Key Issues

LLM-based AI agents and tools are inherently indeterministic. While accuracy is improving, they can still behave in unpredictable or unintended ways, even acting as insider threats — a problem Anthropic calls agentic misalignment. For example, agents may combine APIs at their “will,” introduce errors, or trigger business logic flaws. In one case, a rogue agent caused the complete deletion of a company’s database.

AI agents act to fulfill a goal based on a prompt, without human intuition or common sense. As a result, gaps in authorization or access control, often tied to weak API key usage, become far more dangerous. These risks apply whether the agent is exploited by an external attacker or simply makes a mistake.

10. API Keys Conflate Authentication and Authorization

Lastly, and most broadly, API keys often blur two distinct concerns: authentication, the process of asking “who are you,” and authorization, which asks “what can you do?” They’re often treated like security tokens, but in reality, they’re not completely ideal for either situation. This confusion can lead to engineers placing too much faith in API keys as a security guarantee for all requesting parties.

Alternative Strategies to Bolster API Security

Instead of solely relying on API keys, other security best practices and standards for API access control should be employed. One is a token-based security architecture that uses highly scoped JSON Web Tokens (JWTs), which hold identity and permission claims. This is typically handled using OAuth 2.0, which enables delegated authorization, typically orchestrated by a backend identity server.

In addition to using the reigning architectural standards, another practice is to adopt a zero-trust approach across your authentication and authorization practices. This can include fine-grained permissions for role-based access control or attribute-based access control, applied across both human users and machine-to-machine authentication. System architects should also consider multi-factor authentication that goes beyond API keys.

Lastly, API security practices are evolving to meet the needs of agentic AI. With the dawn of AI agents as a new API consumer type, the concept of just-in-time access has emerged, which allows ephemeral access to AI with intent-based permissions granted in real time.

What API Keys Are Good For

With all that said, there are still legitimate use cases for API keys. For example, when you want to provide quick and easy access to an open API and are not sharing any sort of sensitive data, API keys are typically fine for use.

API keys are also often used by API vendors for tracking account usage, such as for metering and billing purposes. However, this comes with some caveats from a security perspective due to the aforementioned issues.

Integrators: Consider the API Key Vulnerabilities

Today’s interconnected software landscape involves a blend of many internal microservices and third-party SaaS. Many of these components are integrated via APIs, and API keys are still widely deployed for access control.

Yet, API keys are insecure because they are static, lack identity context, and cannot enforce fine-grained access control. Given the unsafe practices and how keys are commonly leaked, they shouldn’t be considered a form of high-grade API security. As such, if you have the option, opt for APIs that do not govern access with API keys. Instead, look for more secure options.

For situations when you must use API keys, it’s a good practice to:

• Rotate them often and store them securely.
• Don’t rely on them as a sole means for identity-based security, authentication, and authorization.
• Complement them with other API authentication methods.

The main takeaway: consider the risks associated with API keys, and avoid treating them as the end-all, be-all for access security or as an identity identifier. Agentic AI requires a serious rethinking of API security, too, and that starts with ensuring it has the correct permissions beyond static API keys.