CVE-2021-21240 : What You Need to Know
Learn about CVE-2021-21240, a denial of service vulnerability in httplib2 < 0.19.0. Understand its impact, affected systems, and mitigation steps to secure Python applications.
Regular expression denial of service vulnerability in httplib2 versions prior to 0.19.0. Exploitation may lead to a denial of service condition due to high CPU consumption during header parsing of a malicious server response.
Understanding CVE-2021-21240
This CVE involves an uncontrolled resource consumption flaw in httplib2 Python library versions < 0.19.0.
What is CVE-2021-21240?
CVE-2021-21240 details a vulnerability in httplib2 that could allow a remote attacker to trigger a denial of service condition by sending a crafted HTTP response.
The Impact of CVE-2021-21240
The impact of this vulnerability is considered high, with an overall base score of 7.5 (High severity) in the CVSS v3.1 scoring system. The attack vector is over the network with no privileges required, potentially leading to a significant availability impact.
Technical Details of CVE-2021-21240
This section provides a deeper insight into the vulnerability in terms of its description, affected systems, and exploitation mechanism.
Vulnerability Description
The vulnerability arises from httplib2's improper handling of long series of characters in the "www-authenticate" header, causing CPU burn while parsing headers.
Affected Systems and Versions
The vulnerability affects httplib2 versions prior to 0.19.0. Users on versions below this are at risk of exploitation.
Exploitation Mechanism
By sending specially crafted HTTP responses with long sequences of certain characters, a malicious actor can trigger the denial of service condition on vulnerable httplib2 clients.
Mitigation and Prevention
To address CVE-2021-21240, it is crucial to take immediate preventive actions and adopt long-term security measures to safeguard systems.
Immediate Steps to Take
Users should update their httplib2 installations to version 0.19.0 or newer to mitigate the vulnerability. Additionally, monitoring network traffic for suspicious activities can help detect exploit attempts.
Long-Term Security Practices
Implementing regular security patches, maintaining up-to-date software versions, and conducting security audits can enhance the overall resilience against similar vulnerabilities.
Patching and Updates
Regularly check for security advisories from the httplib2 project and apply patches promptly to address any new vulnerabilities.