A Missing Release of Memory after Effective Lifetime vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on PTX Series allows an adjacent attacker to cause a Denial of Service (DoS) by sending genuine BGP flowspec packets which cause an FPC heap memory leak. Once having run out of memory the FPC will crash and restart along with a core dump.

Continued receipted of these packets will create a sustained Denial of Service (DoS) condition.

This issue affects Juniper Networks Junos OS on PTX Series:

• All versions prior to 18.4R3-S9;
• 19.1 versions prior to 19.1R3-S7;
• 19.2 versions prior to 19.2R1-S7, 19.2R3-S3;
• 19.3 versions prior to 19.3R2-S6, 19.3R3-S3;
• 19.4 versions prior to 19.4R1-S4, 19.4R3-S6;
• 20.1 versions prior to 20.1R2-S2, 20.1R3;
• 20.2 versions prior to 20.2R3-S1;
• 20.3 versions prior to 20.3R3;
• 20.4 versions prior to 20.4R3;
• 21.1 versions prior to 21.1R2.

Juniper Networks Junos Evolved is not affected.

This issue affects Junos OS devices with the BGP FlowSpec configured:

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

This issue was seen during production usage.

This issue has been assigned  CVE-2021-31367 .

The following software releases have been updated to resolve this specific issue in Junos OS: 18.4R3-S9, 19.1R3-S7, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S3, 19.4R1-S4, 20.1R2-S2, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R3, 21.1R2, 21.2R1, and all subsequent releases.

This issue is being tracked as  1589133 .

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

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-2021-31367: Junos OS: PTX Series: An FPC heap memory leak will be triggered by certain Flowspec route operations which can lead to an FPC crash