XSS Vulnerability in Mistune Package: Exploitable via Unexpected Newlines
Summary
CVE-2017-15612: mistune.py in Mistune 0.7.4 allows XSS via an unexpected newline (such as in java\nscript:) or a crafted email address, related to the escape and autolink functions. Affects mistune across 2 version ranges.
< 0.8-1
< 714e60a20a7efe0923bc39991d989b3ef3324690
Fixed in 0.8-1. How to fix ↓
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Background
Mistune is a popular Markdown parser for Python, designed to convert Markdown text into HTML. It is widely used in various applications due to its speed and ease of use. However, versions prior to 0.8-1 are vulnerable to a cross-site scripting (XSS) attack, which can occur when unexpected newlines or crafted email addresses are processed incorrectly.
Vulnerability Detail
The vulnerability in Mistune arises from improper handling of newlines in user input, particularly in the escape and autolink functions. This flaw allows attackers to inject malicious scripts into web pages, leading to potential data theft, session hijacking, or other malicious activities. The issue is particularly concerning as it can be exploited without user authentication, making it accessible to any user interacting with the affected application.
How To Fix
Minimum fixed version
0.8-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade mistuneTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
If upgrading is not immediately possible, consider sanitizing user input to remove unexpected newlines and validate email addresses before processing them. Implementing a robust input validation mechanism can help mitigate the risk of XSS attacks until the package can be updated.
Conclusion
The XSS vulnerability in the Mistune package poses a significant risk to applications using versions prior to 0.8-1. It is crucial for developers to upgrade to the latest version and implement input validation measures to protect against potential attacks. Utilizing tools like Vulert can aid in monitoring for such vulnerabilities in real-time.
See every vulnerability recorded for mistune →
FAQ
The CVSS score of this vulnerability is 6.1, indicating a medium severity level.
You can use Vulert to monitor and alert for open-source vulnerabilities in your software. Simply upload your manifest file like package-lock.json to check for vulnerabilities.
Exploiting this vulnerability can lead to XSS attacks, allowing attackers to steal sensitive information, hijack user sessions, or perform actions on behalf of users.
Yes, you can sanitize user inputs and implement strict validation for newlines and email addresses to reduce the risk of exploitation until an upgrade can be performed.
Detailed information can be found in the CVE database or through the official Mistune GitHub repository.
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