CVE-2019-0039: Junos OS: Login credentials are vulnerable to brute force attacks through the REST API

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2019-04-10 · updated 2026-06-17
Weakness: CWE-307

Description

If REST API is enabled, the Junos OS login credentials are vulnerable to brute force attacks. The high default connection limit of the REST API may allow an attacker to brute-force passwords using advanced scripting techniques. Additionally, administrators who do not enforce a strong password policy can increase the likelihood of success from brute force attacks. Affected releases are Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D49; 15.1 versions prior to 15.1F6-S12, 15.1R7-S3; 15.1X49 versions prior to 15.1X49-D160; 15.1X53 versions prior to 15.1X53-D236, 15.1X53-D495, 15.1X53-D591, 15.1X53-D69; 16.1 versions prior to 16.1R3-S10, 16.1R4-S12, 16.1R6-S6, 16.1R7-S3; 16.1X65 versions prior to 16.1X65-D49; 16.2 versions prior to 16.2R2-S7; 17.1 versions prior to 17.1R2-S10, 17.1R3; 17.2 versions prior to 17.2R1-S8, 17.2R3-S1; 17.3 versions prior to 17.3R3-S2; 17.4 versions prior to 17.4R1-S6, 17.4R2-S2; 18.1 versions prior to 18.1R2-S4, 18.1R3-S1; 18.2 versions prior to 18.2R1-S5; 18.2X75 versions prior to 18.2X75-D30; 18.3 versions prior to 18.3R1-S1.

Affected products

Juniper Junos OS: from 14.1x53 before 14.1x53-d49; from 15.1 before 15.1f6-s12; from 15.1x49 before 15.1x49-d160; from 15.1x53 before 15.1x53-d236; from 16.1 before 16.1r3-s10; from 16.1x65 before 16.1x65-d49 — fixed in 14.1x53-d49, 15.1f6-s12, 15.1x49-d160, 15.1x53-d236, 16.1r3-s10, 16.1x65-d49

How to fix

Upgrade to a fixed version: Juniper Junos OS 14.1x53-d49, 15.1f6-s12, 15.1x49-d160, 15.1x53-d236. Check the vendor advisory for mitigations.

References

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