CVE-2021-31372 : Vulnerability Insights and Analysis

An Improper Input Validation vulnerability in J-Web of Juniper Networks Junos OS allows a locally authenticated J-Web attacker to escalate their privileges to root over the target device.

Understanding CVE-2021-31372

This CVE affects Juniper Networks Junos OS versions prior to 18.3R3-S5; 18.4 versions prior to 18.4R3-S9; 19.1 versions prior to 19.1R3-S6; 19.2 versions prior to 19.2R3-S3; 19.3 versions prior to 19.3R3-S3; 19.4 versions prior to 19.4R3-S5; 20.1 versions prior to 20.1R3-S1; 20.2 versions prior to 20.2R3-S2; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2, 21.1R3; 21.2 versions prior to 21.2R1-S1, 21.2R2.

What is CVE-2021-31372?

This CVE points to an Improper Input Validation vulnerability in Juniper Networks Junos OS that allows a locally authenticated attacker to gain root privileges over the target device.

The Impact of CVE-2021-31372

The vulnerability poses a high risk with a CVSS base score of 8.8, granting attackers unauthorized high-level access compromising confidentiality, integrity, and availability of the system.

Technical Details of CVE-2021-31372

This vulnerability's attack complexity is low, and the attack vector is through the network. The impact includes high severity on confidentiality, integrity, and availability, with low privileges required.

Vulnerability Description

The issue allows a locally authenticated J-Web attacker to gain root access on the target device.

Affected Systems and Versions

Juniper Networks Junos OS versions mentioned above are vulnerable to this issue.

Exploitation Mechanism

Juniper SIRT has not detected any malicious exploitation related to this vulnerability.

Mitigation and Prevention

To reduce the risk, limit access using access lists or firewall filters to trusted networks, hosts, and users. Alternatively, you can disable J-Web to mitigate the issue.

Immediate Steps to Take

Apply the provided software updates to resolve the vulnerability.

Long-Term Security Practices

Regularly update and patch Juniper Networks Junos OS to ensure all security vulnerabilities are addressed effectively.

Patching and Updates

Juniper Networks has released software updates to address this issue. Install versions 18.3R3-S5, 18.4R3-S9, 19.1R3-S6, 19.2R3-S3, 19.3R3-S3, 19.4R3-S5, 20.1R3-S1, 20.2R3-S2, 20.3R3-S1, 20.4R3, 21.1R2, 21.1R3, 21.2R1-S1, 21.2R2, 21.3R1, or later.