CVE-2021-43309 : Exploit Details and Defense Strategies

An exponential ReDoS (Regular Expression Denial of Service) vulnerability in the uri-template-lite npm package allows an attacker to trigger the vulnerability by providing arbitrary input to the "URI.expand" method.

Understanding CVE-2021-43309

This CVE involves a high impact vulnerability in uri-template-lite package that can lead to Denial of Service (DoS) attacks.

What is CVE-2021-43309?

The CVE-2021-43309 vulnerability pertains to an exponential ReDoS risk in the URI.expand method within the uri-template-lite npm package.

The Impact of CVE-2021-43309

The vulnerability has a CVSS v3.1 base severity rating of MEDIUM (5.9), with a HIGH availability impact due to an attacker-triggered ReDoS.

Technical Details of CVE-2021-43309

This section delves into the specific technical aspects and implications of the CVE.

Vulnerability Description

The vulnerability allows for a significant ReDoS risk when untrusted inputs are processed by the "URI.expand" method in the uri-template-lite package, potentially leading to denial of service attacks.

Affected Systems and Versions

Product: uri-template-lite
Vendor: uri-template-lite
Versions Affected: < 22.9.0

Exploitation Mechanism

The vulnerability can be exploited by providing specially crafted, malicious input to the vulnerable "URI.expand" method, triggering the ReDoS condition.

Mitigation and Prevention

It is crucial to take immediate steps to mitigate and prevent exploitation of this vulnerability.

Immediate Steps to Take

Upgrade to a version of uri-template-lite that is equal to or greater than 22.9.0.
Avoid untrusted input in the URI.expand method.

Long-Term Security Practices

Regularly monitor for security advisories related to uri-template-lite.
Implement input validation and sanitization mechanisms to prevent ReDoS attacks.

Patching and Updates

Keep the uri-template-lite package up to date with the latest security patches and versions to address known vulnerabilities.