CVE detail

CVE-2021-0256 — CVE-2021-0256

Published 2021-04-22 · Modified 2026-06-17 · Vendor juniper · Product junos · Source nvd
MEDIUM
severity
CVSS-derived band
5.5
CVSS v3
0–10 scale
0.0021
EPSS probability
exploitation probability, 30d
11.0%
EPSS percentile
percentile vs all CVEs
NOT LISTED
CISA KEV
known exploited catalog

Description

A sensitive information disclosure vulnerability in the mosquitto message broker of Juniper Networks Junos OS may allow a locally authenticated user with shell access the ability to read portions of sensitive files, such as the master.passwd file. Since mosquitto is shipped with setuid permissions enabled and is owned by the root user, this vulnerability may allow a local privileged user the ability to run mosquitto with root privileges and access sensitive information stored on the local filesystem. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S12, 17.4 versions prior to 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.3 versions prior to 18.3R3-S4; 19.1 versions prior to 19.1R3-S4; 19.3 versions prior to 19.3R3-S1, 19.3R3-S2; 19.4 versions prior to 19.4R2-S

Remediation

vendor remediation guidance

The following software releases have been updated to resolve this specific issue: Junos OS 17.3R3-S12, 17.4R3-S4, 18.1R3-S12, 19.1R3-S4, 19.3R3-S1, 19.3R3-S2, 19.4R2-S3, 20.1R2, 20.2R1-S3, 20.2R2, 20.2R3, 20.3R1, and all subsequent releases.

workarounds

Use access lists or firewall filters to limit access to the device only from trusted hosts. Limit shell access to only trusted system administrators.

ProductVulnerable rangeFixed versionAdvisory
Juniper Networks Junos OS>=17.3<17.3R3-S1217.3R3-S12advisory ↗
Juniper Networks Junos OS>=17.4<17.4R3-S417.4R3-S4advisory ↗
Juniper Networks Junos OS>=18.1<18.1R3-S1218.1R3-S12advisory ↗
Juniper Networks Junos OS>=18.3<18.3R3-S418.3R3-S4advisory ↗
Juniper Networks Junos OS>=19.1<19.1R3-S419.1R3-S4advisory ↗
Juniper Networks Junos OS>=19.3<19.3R3-S1, 19.3R3-S219.3R3-S1, 19.3R3-S2advisory ↗
Juniper Networks Junos OS>=19.4<19.4R2-S319.4R2-S3advisory ↗
Juniper Networks Junos OS>=20.1<20.1R220.1R2advisory ↗
Juniper Networks Junos OS>=20.2<20.2R1-S3, 20.2R2, 20.2R320.2R1-S3, 20.2R2, 20.2R3advisory ↗

References

cvedb.io · NVD · CISA KEV · FIRST EPSS · vendor advisories (CVE Program List v5). Informational only, no warranty — verify every remediation against the vendor advisory before acting on it. This product uses data from the NVD API but is not endorsed or certified by the NVD, CISA, FIRST.org or any vendor named. CVE® is a registered trademark of The MITRE Corporation.