Vulnerability Monitor

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CVE-2021-0256


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-S3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S3, 20.2R2, 20.2R3.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.5, requiring local system access to exploit with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), for affected systems. Impacting 1 product from juniper organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-04-22T20:15:09.527

Last Modified

2026-06-17T03:29:37.533

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 5.5 (MEDIUM)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:P/I:N/A:N

  • Access Vector: LOCAL
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: NONE
  • Availability Impact: NONE
Exploitability Score

3.9

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-250
  • Type: Primary
    CWE-269

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.3 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 17.4 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.1 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.2 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.3 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 18.4 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.1 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.2 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.3 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 19.4 Yes
Operating System juniper junos 20.1 Yes
Operating System juniper junos 20.1 Yes
Operating System juniper junos 20.1 Yes
Operating System juniper junos 20.1 Yes
Operating System juniper junos 20.1 Yes
Operating System juniper junos 20.2 Yes
Operating System juniper junos 20.2 Yes
Operating System juniper junos 20.2 Yes
Operating System juniper junos 20.2 Yes
Operating System juniper junos 20.2 Yes
Operating System juniper junos 20.3 Yes
Operating System juniper junos 20.4 Yes
Operating System juniper junos 20.4 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.