When security testing Python applications, three vulnerability classes appear again and again across web apps, APIs, automation scripts, and internal tooling:
Injection Attacks
Insecure Deserialization
Path Traversal
These weaknesses are especially dangerous because they often lead directly to :
remote code execution (RCE)
data exfiltration or
full system compromise.
As a security tester, your task is not only to understand them conceptually, but to recognise their signatures in real Python code.
Why These Three Matter Most¶
These weaknesses share common properties:
| Weakness | Typical Impact | Exploit Difficulty | Prevalence |
|---|---|---|---|
| Injection | Remote code execution | Low–Medium | Very High |
| Insecure Deserialization | Remote code execution | Medium | High |
| Path Traversal | File disclosure / RCE | Low | Very High |
They frequently appear in:
Flask/Django applications
Internal admin tools
Automation scripts
CI/CD utilities
Data science notebooks
Microservices
Security Tester’s Checklist¶
When auditing a Python codebase:
Always do a SAST scan with Python Code Audit or equivalent.
Trace User Input and analyze origin and possible threads with input from:
HTTP parameters
JSON payloads
File uploads
CLI arguments
Environment variables
Identify Trust Boundaries
Can an external user influence this value?
Is this crossing a network boundary?
Is this stored and later re-used?
In Python security testing, these three weakness classes account for a disproportionate share of critical vulnerabilities. Mastering their detection — in both source review and black-box testing — is a foundational skill for any serious security tester.
In the subsections of this module, these common weaknesses are explained in depth.