Introduction

Modern applications constantly communicate with other systems. They fetch images, call APIs, validate links, and integrate third-party services. Because of this, servers make outbound requests all the time. However, this behaviour introduces a serious risk known as SSRF attacks.

Server-Side Request Forgery (SSRF) attacks occur when an application allows attackers to control where the server sends requests. As a result, attackers can reach internal systems that were never meant to be exposed.

In 2026, SSRF attacks remain one of the most dangerous web vulnerabilities because they bypass firewalls, exploit trust, and expose cloud infrastructure from the inside.

This guide explains how SSRF attacks work, why internal systems get exposed, and how organisations can reduce the risk.

What Is Server-Side Request Forgery (SSRF)?

Server-Side Request Forgery (SSRF) is a vulnerability that allows attackers to make a server send requests to unintended destinations.

Instead of attacking a system directly, the attacker tricks the server into doing it for them.

In simple terms:

The application accepts a URL or network input
The server fetches the resource on behalf of the user
The attacker manipulates the destination

Because the request originates from the server, it often has access to internal networks and trusted services.

Why SSRF Is Especially Dangerous

SSRF attacks are dangerous because they abuse trust and networkposition, not software flaws alone.

Servers sit inside trusted networks

Servers can access internal IPs, services, and metadata endpoints.

Firewalls trust outbound traffic

Many security controls focus on inbound traffic, not server-initiated requests.

Cloud environments amplify the risk

Cloud platforms expose sensitive internal services that SSRF can reach.

As a result, SSRF attacks often lead to severe secondary compromise.

How SSRF Attacks Work

Although implementations vary, SSRF attacks follow a common flow.

Step 1: User-controlled input is accepted

The application allows input such as:

URLs
Image links
Webhooks
File fetch locations

Step 2: The server makes a request

The backend fetches the resource without validating the destination properly.

Step 3: The attacker manipulates the target

Instead of an external URL, the attacker supplies:

Internal IP addresses
Localhost references
Cloud metadata endpoints

Step 4: Internal systems respond

The server receives sensitive data and returns it to the attacker.

Because the request looks legitimate, security controls rarely intervene.

Common SSRF Attack Targets

SSRF attacks focus on internal systems that were never designed for exposure.

Internal APIs

Administrative APIs often lack authentication because they are assumed to be private.

Cloud metadata services

Cloud platforms expose metadata endpoints containing credentials and configuration details.

Databases and caches

Internal services like Redis or Elasticsearch are common SSRF targets.

Local services

Localhost services running on the same server become reachable.

Each exposed service increases the blast radius of the attack.

Real-World SSRF Scenario

A web application allows users to upload profile pictures via URL. The backend fetches the image and stores it.

An attacker submits a URL pointing to an internal metadata service. The server fetches it successfully and returns the response.

Within seconds, the attacker gains access to cloud credentials that allow further compromise.

No firewall rules were bypassed. No malware was deployed. The server simply followed instructions.

This scenario shows why SSRF attacks are so effective.

Why SSRF Attacks Are Hard to Detect

SSRF attacks blend into normal application behaviour.

Requests originate from trusted servers

Logs show valid internal traffic.

No suspicious payloads exist

There is no obvious exploit code.

Responses look legitimate

Sensitive data appears as normal responses.

Attack paths vary

Different services expose different risks.

Because of this, SSRF vulnerabilities often remain hidden for long periods.

Impact on Businesses and Individuals

For Businesses

Exposure of internal services
Cloud credential theft
Infrastructure compromise
Data breaches
Regulatory and compliance risks
Loss of customer trust

For Individuals

Exposure of personal data
Account compromise
Privacy violations
Long-term security consequences

Why SSRF Is a Cloud Security Problem

SSRF attacks have become more severe because of cloud architecture.

Metadata endpoints contain secrets

Cloud metadata services often expose access tokens.

Microservices trust internal traffic

Internal communication is rarely authenticated.

Automation magnifies damage

Compromised credentials enable rapid escalation.

Therefore, SSRF attacks often become full cloud breaches.

How to Prevent SSRF Attacks

Reducing SSRF risk requires strict controls.

Validate and restrict outbound requests

Allow only known domains and protocols.

Block internal IP ranges

Prevent access to localhost and private networks.

Disable unnecessary fetch features

Remove unused URL-fetch functionality.

Harden cloud metadata access

Apply strict access controls and isolation.

Monitor outbound traffic

Unexpected destinations indicate abuse.

Design with zero trust assumptions

Never assume internal requests are safe.

Detailed SSRF prevention guidance is provided by OWASP, which highlights SSRF as a critical web vulnerability: Read more

Why SSRF Is a Design Flaw, Not Just a Bug

SSRF vulnerabilities often arise from design assumptions. Developers assume servers should fetch whatever users provide. However, that assumption ignores how much power servers actually have.

Therefore, preventing SSRF requires rethinking trust boundaries, not just adding filters.

Conclusion

SSRF attacks expose internal systems by turning trusted servers into attack tools. By abusing server-side requests, attackers bypass firewalls, reach private services, and compromise cloud environments.

In 2026, SSRF attacks remain a serious threat because modern applications depend heavily on outbound connectivity. By validating requests, restricting internal access, and designing with zero trust principles, organisations can significantly reduce SSRF risk. At eSHIELD IT Services, we help teams identify SSRF exposure early and secure internal systems before attackers do.

FAQ

What is an SSRF attack?

It forces a server to make requests to unintended destinations.

Why are SSRF attacks dangerous?

They expose internal systems that should never be public.

Are SSRF attacks common in cloud apps?

Yes, especially in applications that fetch URLs.

Do firewalls stop SSRF?

Usually not, because the request originates internally.

Can SSRF lead to full cloud compromise?

Yes, especially through metadata services.

Is SSRF a client-side attack?

No, it occurs entirely on the server side.

Are APIs vulnerable to SSRF?

Yes, if they fetch user-controlled URLs.

Is input validation enough to prevent SSRF?

No, network-level restrictions are also required.