CVE-2020-1660: When DNS filtering is enabled on Juniper Networks Junos MX Series with one of the following cards MS-PIC, MS-MIC or MS-MPC, an incoming stream of pack...

Description

When DNS filtering is enabled on Juniper Networks Junos MX Series with one of the following cards MS-PIC, MS-MIC or MS-MPC, an incoming stream of packets processed by the Multiservices PIC Management Daemon (mspmand) process, responsible for managing "URL Filtering service", may crash, causing the Services PIC to restart. While the Services PIC is restarting, all PIC services including DNS filtering service (DNS sink holing) will be bypassed until the Services PIC completes its boot process. This vulnerability might allow an attacker to cause an extended Denial of Service (DoS) attack against the device and to cause clients to be vulnerable to DNS based attacks by malicious DNS servers when they send DNS requests through the device. As a result, devices which were once protected by the DNS Filtering service are no longer protected and at risk of exploitation. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S8; 18.3 versions prior to 18.3R3-S1; 18.4 versions prior to 18.4R3; 19.1 versions prior to 19.1R3; 19.2 versions prior to 19.2R2; 19.3 versions prior to 19.3R3. This issue does not affect Juniper Networks Junos OS 17.4, 18.1, and 18.2.

Metrics

CVSS 3.1

9.9/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:H

EPSS Probability

0.78%

51.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-362

Affected Software

Vendor	Product	Versions
Juniper	Junos	17.3
Juniper	Junos	18.3
Juniper	Junos	18.4
Juniper	Junos	19.1
Juniper	Junos	19.2
Juniper	Junos	19.3

References

https://kb.juniper.net/JSA11054Vendor Advisory
https://kb.juniper.net/JSA11054Vendor Advisory

Timeline

Published: Oct 16, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-1660?

When DNS filtering is enabled on Juniper Networks Junos MX Series with one of the following cards MS-PIC, MS-MIC or MS-MPC, an incoming stream of packets processed by the Multiservices PIC Management Daemon (mspmand) process, responsible for managing "URL Filtering service", may crash, causing the Services PIC to restart. While the Services PIC is restarting, all PIC services including DNS filtering service (DNS sink holing) will be bypassed until the Services PIC completes its boot process. This vulnerability might allow an attacker to cause an extended Denial of Service (DoS) attack against the device and to cause clients to be vulnerable to DNS based attacks by malicious DNS servers when they send DNS requests through the device. As a result, devices which were once protected by the DNS Filtering service are no longer protected and at risk of exploitation. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S8; 18.3 versions prior to 18.3R3-S1; 18.4 versions prior to 18.4R3; 19.1 versions prior to 19.1R3; 19.2 versions prior to 19.2R2; 19.3 versions prior to 19.3R3. This issue does not affect Juniper Networks Junos OS 17.4, 18.1, and 18.2.

How severe is CVE-2020-1660?

CVE-2020-1660 has a CVSS score of 9.9/10 (CRITICAL severity). The EPSS model estimates a 0.78% probability of exploitation in the next 30 days.

How do I fix CVE-2020-1660?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.