Denial of Service Vulnerability in python-markdown2 Package
Summary
UBUNTU-CVE-2021-26813: markdown2 >=1.0.1.18, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. Affects python-markdown2 versions 2.3.7-2. No fix is published. How to fix ↓
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Background
The python-markdown2 package is a popular Python library that allows users to convert Markdown text into HTML. It is widely used in web applications and content management systems due to its simplicity and efficiency. However, the package has been found to be vulnerable to a regular expression denial of service (ReDoS) attack, which can severely impact its performance and usability.
Vulnerability Detail
The vulnerability, identified as CVE-2021-26813, arises from the use of inefficient regular expressions in the markdown2 library. Attackers can exploit this vulnerability by providing specially crafted input strings that cause excessive backtracking during processing. This can lead to significant delays or even crashes in applications using the library, making it a critical issue for developers relying on markdown2 for rendering Markdown content. The vulnerability has a CVSS score of 7.5, indicating a high severity level.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
If immediate updating is not feasible, consider sanitizing input data to avoid triggering the vulnerability. Implementing input validation can help mitigate the risk until the package is updated.
Conclusion
The python-markdown2 package has a significant vulnerability that can lead to denial of service attacks. It is crucial for developers to update to the patched version to ensure the security and performance of their applications. Regular monitoring for vulnerabilities using tools like Vulert can help maintain software integrity.
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FAQ
CVE-2021-26813 is a vulnerability in the python-markdown2 package that allows for denial of service attacks through specially crafted input strings.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without needing to sign up.
Exploitation of this vulnerability can lead to application slowdowns or crashes, affecting user experience and system reliability.
Yes, the vulnerability has been patched in version 2.4.0 and later of the python-markdown2 package.
If an immediate update is not possible, implement input validation to sanitize user inputs and reduce the risk of exploitation.
References
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