CVE-2021-0256 Junos OS: mosquitto Local Privilege Escalation vulnerability in SUID binaries
Local authenticated users can exploit SUID mosquitto binaries to read sensitive files and escalate privileges to root on Juniper Junos OS devices.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-0256?
CVE-2021-0256 is a medium-severity vulnerability in Juniper Junos, published on 22 Apr 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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-S3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S3, 20.2R2, 20.2R3.
Which versions are affected by CVE-2021-0256?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2021-0256?
No fix has been published for CVE-2021-0256 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-0256 being exploited?
There is no known exploitation of CVE-2021-0256 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-fchr-g73c-p263.