Quick Answer
The answer is reflected cross-site scripting (XSS). This is correct because the tester’s payload, %3Cscript%3Ealert('XSS')%3C/script%3E, is a URL-encoded HTML script tag that the web application decodes and immediately echoes back in the HTTP response without any sanitization or validation. In reflected XSS, the malicious script is reflected off the web server, typically via a crafted link or form submission, and executes in the victim’s browser because the application fails to escape or filter user input before including it in the output. On the Certified Ethical Hacker CEH exam, this scenario tests your ability to distinguish reflected XSS from stored or DOM-based XSS—a common trap is confusing it with stored XSS, but remember that reflected XSS is not permanently stored on the server; it only appears in the immediate response. A helpful memory tip: think of a mirror—reflected XSS bounces the payload right back at you in the response, whereas stored XSS saves it for later.
This CEH practice question tests your understanding of web application and injection attacks. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A tester sends the following payload to a web application: %3Cscript%3Ealert('XSS')%3C/script%3E. The application echoes back the decoded payload in the response without sanitization. This behavior is typical of which type of vulnerability?
HTTP Response Splitting
Why wrong: Response splitting injects headers, not script execution.
DOM-based XSS
Why wrong: DOM-based XSS occurs client-side, not server-side reflection.
Stored XSS
Why wrong: The payload is not stored; it reflects immediately.
Reflected XSS
The input is reflected in the response unsanitized.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Reflected XSS
The payload is URL-encoded HTML and is decoded and reflected, indicating reflected XSS.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
HTTP Response Splitting
Why it's wrong here
Response splitting injects headers, not script execution.
DOM-based XSS
Why it's wrong here
DOM-based XSS occurs client-side, not server-side reflection.
Stored XSS
Why it's wrong here
The payload is not stored; it reflects immediately.
Reflected XSS
Why this is correct
The input is reflected in the response unsanitized.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CEH exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Web Application and Injection Attacks — This question tests Web Application and Injection Attacks — Read the scenario before looking for a memorised answer..
The correct answer is: Reflected XSS — The payload is URL-encoded HTML and is decoded and reflected, indicating reflected XSS.
Identify which CEH exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 21, 2026
This CEH practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CEH exam.
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