CVE-2021-41238 : Security Advisory and Response

Hangfire is an open source system used for background job processing in .NET or .NET Core applications. A vulnerability in version 1.7.25 allows remote unauthorized access to the Dashboard UI, impacting systems with default settings.

Understanding CVE-2021-41238

What is CVE-2021-41238?

Hangfire's Dashboard UI, which previously used authorization filters to restrict remote access, had a flaw in version 1.7.25 that allowed remote requests without authorization. This could lead to unauthorized users accessing sensitive data.

The Impact of CVE-2021-41238

The vulnerability has a base score of 8.6, indicating a high severity issue with a significant impact on confidentiality. Attackers can exploit this issue over the network without requiring privileges, potentially compromising sensitive information.

Technical Details of CVE-2021-41238

Vulnerability Description

In Hangfire version 1.7.25, the absence of default authorization filters in the Dashboard UI allowed remote requests to succeed, compromising the system's security.

Affected Systems and Versions

Product: Hangfire
Vendor: HangfireIO
Vulnerable Version: 1.7.25

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Confidentiality Impact: High
Integrity Impact: Low
Privileges Required: None

Mitigation and Prevention

Immediate Steps to Take

Upgrade to version 1.7.26 or newer to mitigate the vulnerability
For users unable to upgrade, explicitly use the

LocalRequestsOnlyAuthorizationFilter

when configuring the Dashboard UI

Long-Term Security Practices

Regularly review and update authorization settings in Hangfire
Stay informed about security advisories and updates from HangfireIO

Patching and Updates

Patched versions (1.7.26) are available on Nuget.org and GitHub