


What are some common security vulnerabilities in Python web applications (e.g., XSS, SQL injection) and how can they be mitigated?
Jun 10, 2025 am 12:13 AMWeb application security needs to be paid attention to. Common vulnerabilities on Python websites include XSS, SQL injection, CSRF and file upload risks. For XSS, the template engine should be used to automatically escape, filter rich text HTML and set CSP policies; to prevent SQL injection, parameterized query or ORM framework, and verify user input; to prevent CSRF, CSRF Token mechanism must be enabled and sensitive operations are confirmed twice; to file upload vulnerabilities, type, rename files, and execution permissions must be prohibited. Following the norms and using mature tools can effectively reduce risks, and safety needs continuous attention and testing.
The security issues of web applications cannot be ignored, and websites developed by Python are no exception. Common vulnerabilities such as XSS, SQL injection, etc. If they are not handled properly, they may lead to data leakage or even system hacking.
Here are some of the most common security vulnerabilities and how to avoid them.
What is XSS? How to prevent it?
XSS (cross-site scripting attack) refers to an attacker inserting a malicious script into a web page, and when other users browse the page, the script will be executed on their browser. This is often used to steal cookies, hijack sessions, or phish.
Common scenarios:
- When a user submits a comment, the comment content contains the
<script></script>
tag. - The search box returns to the result page and directly displays the search terms on the page without filtering.
Coping method:
- All output content is escaped by default in the template engine. For example, both Jinja2 and Django templates support automatic escape.
- Be especially careful with rich text content, and you can use whitelisting to filter HTML tags.
- Set
Content-Security-Policy
in HTTP header to limit the page to only load scripts from the specified source.
What is SQL injection? How to prevent it?
SQL injection is an attacker by constructing malicious input, bypassing program logic, tampering with or executing database commands. For example, if the login interface does not process the input correctly, it may be bypassed and logged in directly.
For example: Suppose you write SQL statements using string splicing:
query = "SELECT * FROM users WHERE username = '" username "' AND password = '" password "'"
If an attacker enters username = ' OR '1'='1
, it may make the query true forever.
Solution:
- Use parameterized queries (also called precompiled statements), such as using placeholders in
psycopg2
orsqlite3
. - ORM frameworks (such as SQLAlchemy or Django ORM) are naturally anti-injected, and are recommended to use them first.
- Verify and clean the input, and do not blindly trust user input.
How to defend against CSRF attacks?
CSRF (cross-site request forgery) refers to an attacker inducing a user to click on a link or access a certain page, thereby performing operations that are not intended by the user, such as transferring money, modifying passwords, etc.
Typical situation: The user has just logged into a bank website, then clicked on a malicious link to initiate a transfer request.
Protection means:
- Use CSRF Token, add a one-time token to the form and verify it on the server side.
- Frameworks such as Django and Flask-WTF have ready-made CSRF protection mechanisms, and it is recommended to enable and configure them correctly.
- Request a secondary confirmation or verification code for sensitive operations (such as password modification, payment).
What should I pay attention to when uploading a file?
Many websites allow users to upload files, but if restrictions are not made, an attacker may upload executable scripts (such as .php
files) and run them, causing serious consequences.
Risk points:
- Allows uploading of any type of files.
- The file name has not been renamed and an attacker may upload
.htaccess
or.php
file. - The upload directory has execution permission.
Preventive measures:
- Strictly limit file types, use whitelists instead of blacklists.
- Rename the file after uploading to avoid exposing the path of the original file name.
- Place the upload directory in a non-Web root directory, or set prohibition of executing scripts.
- It is safer to upload files using CDN or standalone domain name.
Although these vulnerabilities are common, most of them can be effectively avoided as long as you pay attention to development specifications and use mature frameworks and tools. Safety is a continuous process, and regular scanning and testing should be done after it is launched.
Basically all this is not complicated but easy to ignore.
The above is the detailed content of What are some common security vulnerabilities in Python web applications (e.g., XSS, SQL injection) and how can they be mitigated?. For more information, please follow other related articles on the PHP Chinese website!

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