An Improper Privilege Management vulnerability in the gRPC framework, used by the Juniper Extension Toolkit (JET) API on Juniper Networks Junos OS and Junos OS Evolved, allows a network-based, low-privileged authenticated attacker to perform operations as root, leading to complete compromise of the targeted system.

The issue is caused by the JET service daemon (jsd) process authenticating the user, then passing configuration operations directly to the management daemon (mgd) process, which runs as root.

This issue affects Juniper Networks Junos OS:

• 18.4 versions prior to 18.4R1-S8, 18.4R2-S8, 18.4R3-S8;
• 19.1 versions prior to 19.1R2-S3, 19.1R3-S5;
• 19.2 versions prior to 19.2R1-S7, 19.2R3-S2;
• 19.3 versions prior to 19.3R2-S6, 19.3R3-S2;
• 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S3;
• 20.1 versions prior to 20.1R2-S2, 20.1R3;
• 20.2 versions prior to 20.2R2-S3, 20.2R3;
• 20.3 versions prior to 20.3R2-S1, 20.3R3;
• 20.4 versions prior to 20.4R2.

This issue does not affect Juniper Networks Junos OS versions prior to 18.4R1.

Juniper Networks Junos OS Evolved:

• All versions prior to 20.4R2-EVO;
• 21.1-EVO versions prior to 21.1R2-EVO.

The following is an example of enabling gRPC in Junos:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned  CVE-2021-31350 .
 

The following software releases have been updated to resolve this specific issue:

Junos OS 18.4R1-S8, 18.4R2-S8, 18.4R3-S8, 19.1R2-S3, 19.1R3-S5, 19.2R1-S7, 19.2R3-S2, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2-S1, 20.3R3, 20.4R2, 21.1R1, and all subsequent releases.

Junos OS Evolved 20.4R2-EVO, 21.1R2-EVO, 21.2R1-EVO, and all subsequent releases.

This issue is being tracked as  1578302 .
 

Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 

2021-10-13: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-31350: Privilege escalation vulnerability in Juniper Extension Toolkit (JET)