Quick Answer
The answer is SQL injection, as directly concatenating unsanitized user input into SQL queries creates a classic injection vulnerability. This occurs because the application fails to distinguish between code and data, allowing an attacker to manipulate the query’s structure by inserting malicious SQL commands, such as ' OR 1=1 --, which can bypass authentication or exfiltrate the database. On the Certified Information Systems Security Professional CISSP exam, this concept tests your understanding of secure coding practices within the Software Development Security domain, often appearing in code review scenarios to distinguish it from cross-site scripting or CSRF. A common trap is confusing SQL injection with XSS, but remember: SQL injection targets the database layer, while XSS targets the browser. Memory tip: “Concatenation equals contamination”—when you see direct string building with user input, think SQL injection first.
This CISSP practice question tests your understanding of software development security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
During a code review, a developer notices that an application directly concatenates user input into SQL queries. Which type of vulnerability does this represent?
Cross-site scripting (XSS)
Why wrong: XSS injects client-side scripts into web pages, not SQL.
Cross-site request forgery (CSRF)
Why wrong: CSRF exploits trust in a user's browser, not direct input to queries.
Buffer overflow
Why wrong: Buffer overflow is caused by writing beyond allocated memory, not SQL.
SQL injection
Concatenating user input into SQL queries allows an attacker to modify the query structure.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
SQL injection
Option B is correct because direct concatenation of user input into SQL queries is a classic SQL injection vulnerability. Option A is wrong because XSS involves injecting scripts into web pages. Option C is wrong because CSRF relies on tricking a user's browser. Option D is wrong because buffer overflow is a memory corruption issue.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Cross-site scripting (XSS)
Why it's wrong here
XSS injects client-side scripts into web pages, not SQL.
Cross-site request forgery (CSRF)
Why it's wrong here
CSRF exploits trust in a user's browser, not direct input to queries.
Buffer overflow
Why it's wrong here
Buffer overflow is caused by writing beyond allocated memory, not SQL.
SQL injection
Why this is correct
Concatenating user input into SQL queries allows an attacker to modify the query structure.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISSP NAT questions on configuration and troubleshooting.
Software Development Security — study guide chapter
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FAQ
Software Development Security — This question tests Software Development Security — Static NAT maps one inside address to one outside address..
The correct answer is: SQL injection — Option B is correct because direct concatenation of user input into SQL queries is a classic SQL injection vulnerability. Option A is wrong because XSS involves injecting scripts into web pages. Option C is wrong because CSRF relies on tricking a user's browser. Option D is wrong because buffer overflow is a memory corruption issue.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISSP NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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