Product Affected

This issue affects Junos OS 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4.
Medium
5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

Problem

Multiple local privilege escalation vulnerabilities in Juniper Networks Junos OS have been reported due to the setuid bit being enabled on several binaries. These binaries will run as the owner of the executable (typically “root”) and inherit their privileges. This may allow a locally authenticated user with shell access the ability to disclose sensitive information or execute arbitrary commands as root.

These issues affect Juniper Networks Junos OS:

  • 17.3 versions prior to 17.3R3-S12;
  • 17.4 versions prior to 17.4R2-S13, 17.4R3-S4;
  • 18.1 versions prior to 18.1R3-S12;
  • 18.2 versions prior to 18.2R2-S8, 18.2R3-S7;
  • 18.3 versions prior to 18.3R3-S4;
  • 18.4 versions prior to 18.4R2-S7, 18.4R3-S7;
  • 19.1 versions prior to 19.1R3-S4;
  • 19.2 versions prior to 19.2R3-S2;
  • 19.3 versions prior to 19.3R3-S2;
  • 19.4 versions prior to 19.4R3-S2;
  • 20.1 versions prior to 20.1R2;
  • 20.2 versions prior to 20.2R2-S1, 20.2R3;
  • 20.3 versions prior to 20.3R1-S1, 20.3R2;
  • 20.4 versions prior to 20.4R2.


Juniper SIRT is not aware of any malicious exploitation of these vulnerabilities.

These issues were discovered during external security research.

The following vulnerabilities have been resolved in the releases listed below:

CVE CVSS Summary
CVE-2021-0255 5.5 ( CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N ) Junos OS: ethtraceroute Local Privilege Escalation vulnerability in SUID binaries
CVE-2021-0256 5.5 ( CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N ) Junos OS: mosquitto Local Privilege Escalation vulnerability in SUID binaries

 

Solution

The following software releases have been updated to resolve these specific issues: Junos OS 17.3R3-S12, 17.4R2-S13, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S7, 18.3R3-S4, 18.4R2-S7, 18.4R3-S7, 19.1R3-S4, 19.2R3-S2, 19.3R3-S2, 19.4R3-S2, 20.1R2, 20.2R2-S1, 20.2R3, 20.3R1-S1, 20.3R2, 20.4R2, 21.1R1, and all subsequent releases.

These issues are being tracked as  1529209  and  1529211 .
 

Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 

Workaround

To reduce the risk of malicious exploitation, use access lists or firewall filters to limit CLI access to the device only from trusted, administrative networks or hosts. Additionally, limit access to the Junos OS shell to only trusted system administrators.
 

Severity Assessment

Information for how Juniper Networks uses CVSS can be found at KB 16446 [juniper.net] "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Modification History

2021-04-14: Initial Publication.

Related Information

Acknowledgements

Juniper SIRT would like to acknowledge and thank Hoàng Thạch Nguyễn (d4rkn3ss) of STAR Labs for responsibly reporting this vulnerability.