CVE-2021-31371 Explained : Impact and Mitigation

Juniper Networks Junos OS on QFX5000 Series switches is affected by a vulnerability that may leak configuration information to the Internet, potentially exposing sensitive data.

Understanding CVE-2021-31371

This CVE impacts Juniper Networks Junos OS on specific QFX5000 Series devices, allowing internal network traffic to be forwarded to egress interfaces, leading to an information exposure vulnerability.

What is CVE-2021-31371?

Juniper Networks Junos OS uses the 128.0.0.0/2 subnet for internal communications but may inadvertently leak configuration data to the Internet due to packets egressing the switch.

The Impact of CVE-2021-31371

This vulnerability could expose information such as heartbeats and kernel versions, potentially aiding malicious actors in crafting targeted attacks.

Technical Details of CVE-2021-31371

This vulnerability has a CVSS v3.1 base score of 5.3 (Medium severity) with a low attack complexity and impact on confidentiality. No known exploits have been reported.

Vulnerability Description

Due to a flaw in internal communication handling, packets with specific IP addresses can leak sensitive data, affecting various QFX5000 Series versions.

Affected Systems and Versions

All Juniper Networks Junos OS versions on QFX5000 Series devices prior to specific releases are vulnerable to this information exposure flaw.

Exploitation Mechanism

No malicious exploitation of this vulnerability has been reported by Juniper SIRT, but the potential for targeted attacks exists.

Mitigation and Prevention

If you are using an affected Junos OS version, immediate action is recommended to prevent information leakage and enhance network security.

Immediate Steps to Take

Ensure you update Junos OS to the patched versions provided by Juniper Networks to mitigate the risk of information exposure.

Long-Term Security Practices

Implement firewall filters to discard internal network packets and consider additional network segmentation for enhanced security.

Patching and Updates

Juniper Networks has released updated software versions to address this vulnerability, including subsequent releases after the patched versions.