CVE-2021-31350

Junos OS and Junos OS Evolved: Privilege escalation vulnerability in Juniper Extension Toolkit (JET)

HIGH

8.8

CVSS Score

Published: October 19, 2021 at 06:16 PM UTC

Updated: June 17, 2026 at 03:51 AM UTC

3 products affected across 2 vendorsJunosJunos OS EvolvedJunos OS Evolved

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Severity

HIGH8.8

Exploit prediction

EPSS 0.9%

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

18.4 ≤ v < 18.4R1-S8, 18.4R2-S8, 18.4R3-S819.1 ≤ v < 19.1R2-S3, 19.1R3-S519.2 ≤ v < 19.2R1-S7, 19.2R3-S219.3 ≤ v < 19.3R2-S6, 19.3R3-S219.4 ≤ v < 19.4R1-S4, 19.4R2-S4, 19.4R3-S320.1 ≤ v < 20.1R2-S2, 20.1R320.2 ≤ v < 20.2R2-S3, 20.2R320.3 ≤ v < 20.3R2-S1, 20.3R320.4 ≤ v < 20.4R218.4 18.4 r1 18.4 r1-s1 18.4 r1-s2 18.4 r1-s3 18.4 r1-s4 18.4 r1-s5 18.4 r1-s6 18.4 r1-s7 18.4 r2-s8 18.4 r3-s8 19.1 19.1 r1 19.1 r1-s1 19.1 r1-s2 19.1 r1-s3 19.1 r1-s4 19.1 r1-s5 19.1 r1-s6 19.1 r2 19.1 r2-s1 19.1 r2-s2 19.1 r3-s5 19.2 19.2 r1 19.2 r1-s1 19.2 r1-s2 19.2 r1-s3 19.2 r1-s4 19.2 r1-s5 19.2 r1-s6 19.2 r3-s2 19.3 19.3 r1 19.3 r1-s1 19.3 r2 19.3 r2-s1 19.3 r2-s2 19.3 r2-s3 19.3 r2-s4 19.3 r2-s5 19.3 r3-s2 19.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r1-s3 19.4 r2-s4 19.4 r3-s3 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.1 r2 20.1 r2-s1 20.1 r3 20.2 20.2 r1 20.2 r1-s1 20.2 r1-s2 20.2 r1-s3 20.2 r2 20.2 r2-s1 20.2 r2-s2 20.2 r3 20.3 20.3 r1 20.3 r1-s1 20.3 r2 20.3 r3 20.4 20.4 r1 20.4 r1-s1

Vendor states this is fixed in 18.4R1 (unaffected)

Affected range stops below 18.4R1-S8, 18.4R2-S8, 18.4R3-S8, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.1R2-S3, 19.1R3-S5, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.2R1-S7, 19.2R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.3R2-S6, 19.3R3-S2, so it looks safe — our inference, not a vendor statement

Affected range stops below 19.4R1-S4, 19.4R2-S4, 19.4R3-S3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2-S2, 20.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R2-S3, 20.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R2-S1, 20.3R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.4R2, so it looks safe — our inference, not a vendor statement

Junos OS Evolved · Juniper Networks

60%

v < 20.4R2-EVO21.1-EVO ≤ v < 21.1R2-EVO21.1-EVO

Affected range stops below 20.4R2-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 21.1R2-EVO, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://kb.juniper.net/JSA11215

References (1)

x_refsource_CONFIRMPatchVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11215

CVSS

8.8HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: LOW
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-269

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