A vulnerability in the processing of traffic matching a firewall filter containing a syslog action in Juniper Networks Junos OS on MX Series with MPC10/MPC11 cards installed, PTX10003 and PTX10008 Series devices, will cause the line card to crash and restart, creating a Denial of Service (DoS). Continued receipt and processing of packets matching the firewall filter can create a sustained Denial of Service (DoS) condition.

When traffic hits the firewall filter, configured on lo0 or any physical interface on the line card, containing a term with a syslog action (e.g. 'term <name> then syslog'), the affected line card will crash and restart, impacting traffic processing through the ports of the line card.

This issue only affects MX Series routers with MPC10 or MPC11 line cards, and PTX10003 or PTX10008 Series packet transport routers.

No other platforms or models of line cards are affected by this issue.

Note: This issue has also been identified and described in technical service bulletin TSB17931 [juniper.net] (login required).

This issue affects:

• Juniper Networks Junos OS on MX Series:
• 19.3 versions prior to 19.3R3-S2;
• 19.4 versions prior to 19.4R3-S2;
• 20.1 versions prior to 20.1R3;
• 20.2 versions prior to 20.2R2-S2, 20.2R3;
• 20.3 versions prior to 20.3R3;
• 20.4 versions prior to 20.4R2.

Juniper Networks Junos OS Evolved on PTX10003, PTX10008:

• All versions prior to 20.4R2-EVO.

This issue does not affect Juniper Networks Junos OS versions prior to 19.3R1.

An example of a vulnerable configuration is shown below:

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-2021-0264 .
 

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

Junos OS: 19.4R3-S2, 20.1R3, 20.2R2-S2, 20.2R3, 20.3R3, 20.4R2, 21.1R1, and all subsequent releases.
Junos OS Evolved: 20.4R2-EVO, 21.1R1-EVO, and all subsequent releases.

This issue is being tracked as  1559174 .
 

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

2021-04-14: 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 Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0264 at cve.mitre.org