CVE-2021-40839 : Exploit Details and Defense Strategies
Learn about CVE-2021-40839, a vulnerability in the rencode package for Python that allows an infinite loop in typecode decoding. Understand the impact and mitigation steps.
This CVE article provides an overview of a vulnerability in the rencode package for Python that allows an infinite loop in typecode decoding, potentially leading to a remote attack that consumes CPU and memory.
Understanding CVE-2021-40839
CVE-2021-40839 is a vulnerability in the rencode package for Python that can be exploited to cause an infinite loop in typecode decoding.
What is CVE-2021-40839?
The rencode package through version 1.0.6 for Python contains a vulnerability that can be triggered by decoding certain typecodes (such as ;\x2f\x7f), resulting in an infinite loop. This flaw can be exploited remotely, causing excessive consumption of CPU and memory resources.
The Impact of CVE-2021-40839
This vulnerability could be leveraged by an attacker to launch a denial-of-service (DoS) attack by overloading the target system's CPU and memory resources.
Technical Details of CVE-2021-40839
This section covers specific technical details of the CVE.
Vulnerability Description
The vulnerability in the rencode Python package allows for an infinite loop in typecode decoding, which can be exploited remotely.
Affected Systems and Versions
- Product: Not applicable
- Vendor: Not applicable
- Versions affected: up to version 1.0.6
Exploitation Mechanism
The vulnerability can be exploited by providing specific typecodes to the decoding function in the rencode package, such as ;\x2f\x7f, to trigger the infinite loop.
Mitigation and Prevention
Here are the steps to mitigate and prevent the exploitation of CVE-2021-40839:
Immediate Steps to Take
- Update the rencode package to a non-vulnerable version.
- Monitor system resources for unusual consumption that may indicate an attack.
Long-Term Security Practices
- Regularly update all software packages to the latest versions.
- Implement network filtering to block potentially harmful requests.
Patching and Updates
- Stay informed about security advisories from the rencode package maintainers.
- Apply patches promptly to address known vulnerabilities.