CVE-2021-33056 Explained : Impact and Mitigation

Belledonne Belle-sip before 4.5.20, as used in Linphone and other products, can crash via an invalid From header in a SIP message.

Understanding CVE-2021-33056

This CVE identifies a vulnerability in Belledonne Belle-sip before version 4.5.20, which can lead to a crash when processing a SIP message with an invalid From header.

What is CVE-2021-33056?

CVE-2021-33056 is a security vulnerability in Belle-sip, impacting versions prior to 4.5.20. This vulnerability may result in a crash by exploiting an invalid From header in a SIP message.

The Impact of CVE-2021-33056

The vulnerability can be exploited by an attacker to crash affected systems, potentially leading to denial of service (DoS) conditions. It poses a risk to the stability and availability of services utilizing the affected versions of Belle-sip.

Technical Details of CVE-2021-33056

This section delves into the specifics of the vulnerability, including its description, affected systems, versions, and the exploitation mechanism.

Vulnerability Description

The vulnerability in Belle-sip before 4.5.20 allows for a crash to occur when processing a SIP message that contains an invalid From header, posing a risk to the integrity of the system.

Affected Systems and Versions

Belledonne Belle-sip versions prior to 4.5.20 are impacted by this vulnerability, including instances where it is utilized in products such as Linphone.

Exploitation Mechanism

By sending a specially crafted SIP message with an invalid From header, an attacker can trigger the vulnerability and potentially crash the system running the affected version of Belle-sip.

Mitigation and Prevention

To address and mitigate the risks associated with CVE-2021-33056, immediate steps, long-term security practices, and the importance of patching and updates are outlined below.

Immediate Steps to Take

It is recommended to update to version 4.5.20 or later of Belle-sip to prevent exploitation of this vulnerability. Additionally, network segmentation and firewall rules can help reduce exposure.

Long-Term Security Practices

Implementing secure coding practices, regular security assessments, and staying informed about software vulnerabilities are crucial for long-term security posture.

Patching and Updates

Regularly applying security patches and updates provided by software vendors is essential to ensure system resilience and protect against known vulnerabilities.