What is the severity of CVE-2021-0256?

CVE-2021-0256 has a CVSS score of 6.5, indicating a medium severity level.

How do I fix CVE-2021-0256?

To remediate CVE-2021-0256, update the Junos OS to a version that addresses this vulnerability as specified in the vendor's security advisory.

Who is affected by CVE-2021-0256?

CVE-2021-0256 affects local authenticated users with shell access on specific versions of Juniper Networks Junos OS using the mosquitto message broker.

What information can be exposed in CVE-2021-0256?

CVE-2021-0256 allows access to sensitive files, potentially exposing content like the master.passwd file.

What is the impact of CVE-2021-0256?

The impact of CVE-2021-0256 is a sensitive information disclosure that could lead to unauthorized access to critical system files.

Vulnerability/
CVE-2021-0256

medium

5.5

CWE

269 250

14/4/2021

3/8/2024

CVE-2021-0256: Junos OS: mosquitto Local Privilege Escalation vulnerability in SUID binaries

First published: Wed Apr 14 2021(Updated: )

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.

Credit: sirt@juniper.net

Affected Software	Affected Version	How to fix
Junos OS Evolved	=17.3
Junos OS Evolved	=17.3-r1
Junos OS Evolved	=17.3-r1-s1
Junos OS Evolved	=17.3-r1-s4
Junos OS Evolved	=17.3-r2
Junos OS Evolved	=17.3-r2-s1
Junos OS Evolved	=17.3-r2-s2
Junos OS Evolved	=17.3-r2-s3
Junos OS Evolved	=17.3-r2-s4
Junos OS Evolved	=17.3-r2-s5
Junos OS Evolved	=17.3-r3
Junos OS Evolved	=17.3-r3
Junos OS Evolved	=17.3-r3-s1
Junos OS Evolved	=17.3-r3-s10
Junos OS Evolved	=17.3-r3-s11
Junos OS Evolved	=17.3-r3-s2
Junos OS Evolved	=17.3-r3-s3
Junos OS Evolved	=17.3-r3-s4
Junos OS Evolved	=17.3-r3-s5
Junos OS Evolved	=17.3-r3-s6
Junos OS Evolved	=17.3-r3-s7
Junos OS Evolved	=17.3-r3-s8
Junos OS Evolved	=17.3-r3-s9
Junos OS Evolved	=17.4
Junos OS Evolved	=17.4-r1
Junos OS Evolved	=17.4-r1-s1
Junos OS Evolved	=17.4-r1-s2
Junos OS Evolved	=17.4-r1-s3
Junos OS Evolved	=17.4-r1-s4
Junos OS Evolved	=17.4-r1-s5
Junos OS Evolved	=17.4-r1-s6
Junos OS Evolved	=17.4-r1-s7
Junos OS Evolved	=17.4-r2
Junos OS Evolved	=17.4-r2-s1
Junos OS Evolved	=17.4-r2-s10
Junos OS Evolved	=17.4-r2-s11
Junos OS Evolved	=17.4-r2-s12
Junos OS Evolved	=17.4-r2-s2
Junos OS Evolved	=17.4-r2-s3
Junos OS Evolved	=17.4-r2-s4
Junos OS Evolved	=17.4-r2-s5
Junos OS Evolved	=17.4-r2-s6
Junos OS Evolved	=17.4-r2-s7
Junos OS Evolved	=17.4-r2-s8
Junos OS Evolved	=17.4-r2-s9
Junos OS Evolved	=17.4-r3
Junos OS Evolved	=17.4-r3-s1
Junos OS Evolved	=17.4-r3-s2
Junos OS Evolved	=17.4-r3-s3
Junos OS Evolved	=18.1
Junos OS Evolved	=18.1-r1
Junos OS Evolved	=18.1-r2
Junos OS Evolved	=18.1-r2-s1
Junos OS Evolved	=18.1-r2-s2
Junos OS Evolved	=18.1-r2-s4
Junos OS Evolved	=18.1-r3
Junos OS Evolved	=18.1-r3-s1
Junos OS Evolved	=18.1-r3-s10
Junos OS Evolved	=18.1-r3-s11
Junos OS Evolved	=18.1-r3-s2
Junos OS Evolved	=18.1-r3-s3
Junos OS Evolved	=18.1-r3-s4
Junos OS Evolved	=18.1-r3-s5
Junos OS Evolved	=18.1-r3-s6
Junos OS Evolved	=18.1-r3-s7
Junos OS Evolved	=18.1-r3-s8
Junos OS Evolved	=18.1-r3-s9
Junos OS Evolved	=18.2
Junos OS Evolved	=18.2-r1
Junos OS Evolved	=18.2-r1-s2
Junos OS Evolved	=18.2-r1-s3
Junos OS Evolved	=18.2-r1-s4
Junos OS Evolved	=18.2-r1-s5
Junos OS Evolved	=18.2-r2
Junos OS Evolved	=18.2-r2-s1
Junos OS Evolved	=18.2-r2-s2
Junos OS Evolved	=18.2-r2-s3
Junos OS Evolved	=18.2-r2-s4
Junos OS Evolved	=18.2-r2-s5
Junos OS Evolved	=18.2-r2-s6
Junos OS Evolved	=18.2-r2-s7
Junos OS Evolved	=18.2-r3
Junos OS Evolved	=18.2-r3-s1
Junos OS Evolved	=18.2-r3-s2
Junos OS Evolved	=18.2-r3-s3
Junos OS Evolved	=18.2-r3-s4
Junos OS Evolved	=18.2-r3-s5
Junos OS Evolved	=18.2-r3-s6
Junos OS Evolved	=18.3
Junos OS Evolved	=18.3-r1
Junos OS Evolved	=18.3-r1-s1
Junos OS Evolved	=18.3-r1-s2
Junos OS Evolved	=18.3-r1-s3
Junos OS Evolved	=18.3-r1-s4
Junos OS Evolved	=18.3-r1-s5
Junos OS Evolved	=18.3-r1-s6
Junos OS Evolved	=18.3-r2
Junos OS Evolved	=18.3-r2-s1
Junos OS Evolved	=18.3-r2-s2
Junos OS Evolved	=18.3-r2-s3
Junos OS Evolved	=18.3-r2-s4
Junos OS Evolved	=18.3-r3
Junos OS Evolved	=18.3-r3-s1
Junos OS Evolved	=18.3-r3-s2
Junos OS Evolved	=18.3-r3-s3
Junos OS Evolved	=18.4
Junos OS Evolved	=18.4-r1
Junos OS Evolved	=18.4-r1-s1
Junos OS Evolved	=18.4-r1-s2
Junos OS Evolved	=18.4-r1-s3
Junos OS Evolved	=18.4-r1-s4
Junos OS Evolved	=18.4-r1-s5
Junos OS Evolved	=18.4-r1-s6
Junos OS Evolved	=18.4-r1-s7
Junos OS Evolved	=18.4-r2
Junos OS Evolved	=18.4-r2-s1
Junos OS Evolved	=18.4-r2-s2
Junos OS Evolved	=18.4-r2-s3
Junos OS Evolved	=18.4-r2-s4
Junos OS Evolved	=18.4-r2-s5
Junos OS Evolved	=18.4-r2-s6
Junos OS Evolved	=18.4-r3
Junos OS Evolved	=18.4-r3-s1
Junos OS Evolved	=18.4-r3-s2
Junos OS Evolved	=18.4-r3-s3
Junos OS Evolved	=18.4-r3-s4
Junos OS Evolved	=18.4-r3-s5
Junos OS Evolved	=18.4-r3-s6
Junos OS Evolved	=19.1
Junos OS Evolved	=19.1-r1
Junos OS Evolved	=19.1-r1-s1
Junos OS Evolved	=19.1-r1-s2
Junos OS Evolved	=19.1-r1-s3
Junos OS Evolved	=19.1-r1-s4
Junos OS Evolved	=19.1-r1-s5
Junos OS Evolved	=19.1-r2
Junos OS Evolved	=19.1-r2-s1
Junos OS Evolved	=19.1-r3
Junos OS Evolved	=19.1-r3-s1
Junos OS Evolved	=19.1-r3-s2
Junos OS Evolved	=19.1-r3-s3
Junos OS Evolved	=19.2
Junos OS Evolved	=19.2-r1
Junos OS Evolved	=19.2-r1-s1
Junos OS Evolved	=19.2-r1-s2
Junos OS Evolved	=19.2-r1-s3
Junos OS Evolved	=19.2-r1-s4
Junos OS Evolved	=19.2-r1-s5
Junos OS Evolved	=19.2-r2
Junos OS Evolved	=19.2-r2-s1
Junos OS Evolved	=19.2-r3
Junos OS Evolved	=19.2-r3-s1
Junos OS Evolved	=19.3
Junos OS Evolved	=19.3-r1
Junos OS Evolved	=19.3-r1-s1
Junos OS Evolved	=19.3-r2
Junos OS Evolved	=19.3-r2-s1
Junos OS Evolved	=19.3-r2-s2
Junos OS Evolved	=19.3-r2-s3
Junos OS Evolved	=19.3-r2-s4
Junos OS Evolved	=19.3-r2-s5
Junos OS Evolved	=19.3-r3
Junos OS Evolved	=19.4-r1
Junos OS Evolved	=19.4-r1-s1
Junos OS Evolved	=19.4-r1-s2
Junos OS Evolved	=19.4-r2
Junos OS Evolved	=19.4-r2-s1
Junos OS Evolved	=19.4-r2-s2
Junos OS Evolved	=19.4-r3
Junos OS Evolved	=19.4-r3-s1
Junos OS Evolved	=20.1-r1
Junos OS Evolved	=20.1-r1-s1
Junos OS Evolved	=20.1-r1-s2
Junos OS Evolved	=20.1-r1-s3
Junos OS Evolved	=20.1-r1-s4
Junos OS Evolved	=20.2-r1
Junos OS Evolved	=20.2-r1-s1
Junos OS Evolved	=20.2-r1-s2
Junos OS Evolved	=20.2-r1-s3
Junos OS Evolved	=20.2-r2
Junos OS Evolved	=20.3-r1
Junos OS Evolved	=20.4-r1
Junos OS Evolved	=20.4-r1-s1

Remedy

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.

Never miss a vulnerability like this again

Reference Links

https://kb.juniper.net/JSA11175

Frequently Asked Questions

What is the severity of CVE-2021-0256?
CVE-2021-0256 has a CVSS score of 6.5, indicating a medium severity level.
How do I fix CVE-2021-0256?
To remediate CVE-2021-0256, update the Junos OS to a version that addresses this vulnerability as specified in the vendor's security advisory.
Who is affected by CVE-2021-0256?
CVE-2021-0256 affects local authenticated users with shell access on specific versions of Juniper Networks Junos OS using the mosquitto message broker.
What information can be exposed in CVE-2021-0256?
CVE-2021-0256 allows access to sensitive files, potentially exposing content like the master.passwd file.
What is the impact of CVE-2021-0256?
The impact of CVE-2021-0256 is a sensitive information disclosure that could lead to unauthorized access to critical system files.

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