In Point to MultiPoint (P2MP) scenarios within established sessions between network or adjacent neighbors the improper use of a source to destination copy write operation combined with a Stack-based Buffer Overflow on certain specific packets processed by the routing protocol daemon (RPD) of Juniper Networks Junos OS and Junos OS Evolved sent by a remote unauthenticated network attacker causes the RPD to crash causing a Denial of Service (DoS).

Continued receipt and processing of these packets will create a sustained Denial of Service (DoS) condition.

This issue affects:

Juniper Networks Junos OS

• 19.2 versions prior to 19.2R3-S2;
• 19.3 versions prior to 19.3R2-S6, 19.3R3-S2;
• 19.4 versions prior to 19.4R1-S4, 19.4R2-S4, 19.4R3-S3;
• 20.1 versions prior to 20.1R2-S2, 20.1R3;
• 20.2 versions prior to 20.2R2-S3, 20.2R3;
• 20.3 versions prior to 20.3R2.

This issue does not affect Juniper Networks Junos OS versions prior to 19.2R1.

Juniper Networks Junos OS Evolved

• 20.1 versions prior to 20.1R3-EVO;
• 20.2 versions prior to 20.2R3-EVO;

20.3 versions prior to 20.3R2-EVO.

The following configuration is required for Junos OS:

The following configuration is required for Junos OS Evolved:

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned  CVE-2021-31383 .

The following software releases have been updated to resolve this specific issue:

Junos OS: 19.2R3-S2, 19.3R2-S6, 19.3R3-S2, 19.4R1-S4, 19.4R2-S4, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R2-S3, 20.2R3, 20.3R2, 20.4R1, and all subsequent releases.

Junos OS Evolved: 20.1R3-EVO, 20.2R3-EVO, 20.3R2-EVO, 20.4R1-EVO, and all subsequent releases.

This issue is being tracked as  1558672 .

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

For Junos OS you can remove the traffic-statistics from the configuration to work around this issue.

For Junos OS Evolved there are no viable workarounds for this issue.

2021-10-13: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-31383 at cve.mitre.org