The answer is that the most significant security concern when a security fix is reverted in Git history is the re-exposure of the application to the original authentication bypass vulnerability. This is because reverting a critical security patch effectively undoes the protective code, creating a regression that re-introduces the exact flaw the fix was designed to eliminate. On the CISSP exam, this scenario tests your understanding of secure software development lifecycle practices, specifically change management and the principle that reverting a security fix is a high-risk regression, not a minor administrative error. A common trap is to focus on commit message clarity or timestamp order, but the core issue is the reintroduced vulnerability itself. Memory tip: think of a security fix as a locked door—reverting it is like taking the lock back off, leaving the vulnerability wide open again.
CISSP Software Development Security Practice Question
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.
Exhibit
Refer to the exhibit.
```
# Git log output
commit 3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b
Author: Developer A <dev.a@company.com>
Date: Mon Jan 15 14:30:00 2024 -0500
Revert "Fix authentication bypass vulnerability"
This reverts commit 1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b.
commit 1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b
Author: Developer B <dev.b@company.com>
Date: Sun Jan 14 10:15:00 2024 -0500
Fix authentication bypass vulnerability
```
Refer to the exhibit. A security auditor examines the Git history of a critical security patch. What is the most significant security concern?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The security fix was reverted, re-exposing the application to the authentication bypass vulnerability.
Option D is correct because a developer reverted a security fix, re-introducing the vulnerability. This is a serious regression. Option A is wrong while commitment discipline is informal, the bigger issue is the revert. Option B is wrong because the timestamps show the revert happened after the fix. Option C is wrong because the commit message explicitly says it reverts the fix, so the intent is clear.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The security fix was reverted, re-exposing the application to the authentication bypass vulnerability.
Why this is correct
Reversing the fix reintroduces the vulnerability.
Related concept
Static NAT maps one inside address to one outside address.
✗
Developer A and Developer B are not following a formal commitment process.
Why it's wrong here
While true, the key issue is the security regression.
✗
The commit message of the revert does not explain why the vulnerability fix was removed.
Why it's wrong here
The message clearly states it reverts the fix.
✗
The fix was authored by Developer B but reverted by Developer A without approval.
Why it's wrong here
Lack of approval is a process issue, but the security vulnerability is the main concern.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
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
How to think about this question
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.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
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
How this comes up in practice
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
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 — This question tests Software Development Security — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The security fix was reverted, re-exposing the application to the authentication bypass vulnerability. — Option D is correct because a developer reverted a security fix, re-introducing the vulnerability. This is a serious regression. Option A is wrong while commitment discipline is informal, the bigger issue is the revert. Option B is wrong because the timestamps show the revert happened after the fix. Option C is wrong because the commit message explicitly says it reverts the fix, so the intent is clear.
What should I do if I get this CISSP question wrong?
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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