CVE-2021-31808 : Security Advisory and Response

An input-validation bug in Squid before 4.15 and 5.x before 5.0.6 allows a Denial of Service attack via an HTTP Range request.

Understanding CVE-2021-31808

This CVE identifies a vulnerability in Squid versions before 4.15 and 5.x before 5.0.6 that can be exploited for a Denial of Service attack.

What is CVE-2021-31808?

The issue in Squid results from an input-validation bug, enabling a specific HTTP request to cause a Denial of Service condition impacting all proxy users.

The Impact of CVE-2021-31808

The vulnerability in Squid could lead to a complete disruption of service by maliciously crafted HTTP Range requests, affecting proxy clients.

Technical Details of CVE-2021-31808

The technical aspects of the CVE include vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

Squid versions prior to 4.15 and 5.x before 5.0.6 are susceptible to a Denial of Service attack triggered by a certain type of HTTP request.

Affected Systems and Versions

All Squid versions before 4.15 and 5.x before 5.0.6 are impacted by this vulnerability.

Exploitation Mechanism

Exploiting this CVE involves sending a malicious HTTP Range request to the Squid proxy server, causing a DoS condition.

Mitigation and Prevention

Protecting systems against CVE-2021-31808 involves taking immediate steps and adopting long-term security practices.

Immediate Steps to Take

Update Squid to version 4.15 or 5.0.6 to mitigate the vulnerability.
Implement network-based controls to filter out potentially malicious HTTP requests.

Long-Term Security Practices

Regularly update and patch Squid installations to prevent known vulnerabilities.
Monitor network traffic for any anomalous HTTP Range requests that may indicate exploitation attempts.

Patching and Updates

Stay informed about security advisories and patches released by Squid to address vulnerabilities like CVE-2021-31808.