What is CVE-2021-31350?

CVE-2021-31350 is a high-severity vulnerability in Juniper Junos, classified under Improper Privilege Management. CVSS score: 7.5/10. Published 2021-10-19.

How severe is CVE-2021-31350?

High severity. CVSS v3 base score is 7.5 out of 10.

Privilege escalation in Juniper Junos

CVE-2021-31350

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.

Vulnerability class: Privilege Escalation

Published 2021-10-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.5th percentile), scored 2026-10-03.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 57th percentile — 57.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Juniper Junos — versions 18.4, 19.1, 19.2
Juniper Junos OS Evolved — versions 18.3, 19.1, 19.2
Juniper Networks Junos OS — versions unspecified, 18.4, 19.1
Juniper Networks Junos OS Evolved — versions unspecified, 21.1-EVO

Weakness classification (CWE)

CWE-269 — Improper Privilege Management

References

kb.juniper.net/JSA11215 (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2021-31350?: CVE-2021-31350 is a high-severity vulnerability in Juniper Junos, classified under Improper Privilege Management. CVSS score: 7.5/10. Published 2021-10-19.
How severe is CVE-2021-31350?: High severity. CVSS v3 base score is 7.5 out of 10.