CVE-2020-15233 : Security Advisory and Response

ORY Fosite is a security first OAuth2 & OpenID Connect framework for Go. In Fosite from version 0.30.2 and before version 0.34.1, there is a vulnerability that allows attackers to override the registered redirect URL by manipulating the OAuth flow.

Understanding CVE-2020-15233

This CVE highlights a security issue in ORY Fosite versions prior to 0.34.1 that enables attackers to manipulate redirect URLs.

What is CVE-2020-15233?

ORY Fosite versions 0.30.2 to 0.34.1 are susceptible to an exploit where attackers can override the registered redirect URL by abusing the OAuth flow.
Attackers can modify the redirect URL to a loopback adapter, allowing them to insert custom URL query parameters and change the host of the registered redirect URL.
This vulnerability is only exploitable when the attacker has access to the loopback interface.

The Impact of CVE-2020-15233

CVSS Score: 6.1 (Medium)
Attack Vector: Network
Confidentiality Impact: High
Integrity Impact: High
Privileges Required: High
User Interaction: Required
This vulnerability poses a medium risk with high impacts on confidentiality and integrity.

Technical Details of CVE-2020-15233

ORY Fosite's vulnerability allows attackers to manipulate redirect URLs, potentially leading to security breaches.

Vulnerability Description

The issue arises from a lack of proper validation in handling redirect URLs, enabling attackers to override them.

Affected Systems and Versions

ORY Fosite versions prior to 0.34.1 are affected by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the OAuth flow and redirecting URLs to loopback adapters.

Mitigation and Prevention

Taking immediate steps and implementing long-term security practices are crucial to mitigate the risks associated with CVE-2020-15233.

Immediate Steps to Take

Update ORY Fosite to version 0.34.1 or newer to patch the vulnerability.
Monitor and restrict access to the loopback interface to prevent potential attacks.

Long-Term Security Practices

Implement strict input validation mechanisms to prevent URL manipulation attacks.
Regularly review and update security configurations to address emerging threats.

Patching and Updates

Regularly check for security advisories and updates from ORY Fosite to stay protected against known vulnerabilities.