CVE-2020-1681: Receipt of a specifically malformed NDP packet sent from the local area network (LAN) to a device running Juniper Networks Junos OS Evolved can cause ...

Description

Receipt of a specifically malformed NDP packet sent from the local area network (LAN) to a device running Juniper Networks Junos OS Evolved can cause the ndp process to crash, resulting in a Denial of Service (DoS). The process automatically restarts without intervention, but a continuous receipt of the malformed NDP packets could leaded to an extended Denial of Service condition. During this time, IPv6 neighbor learning will be affected. The issue occurs when parsing the incoming malformed NDP packet. Rather than simply discarding the packet, the process asserts, performing a controlled exit and restart, thereby avoiding any chance of an unhandled exception. Exploitation of this vulnerability is limited to a temporary denial of service, and cannot be leveraged to cause additional impact on the system. This issue is limited to the processing of IPv6 NDP packets. IPv4 packet processing cannot trigger, and is unaffected by this vulnerability. This issue affects all Juniper Networks Junos OS Evolved versions prior to 20.1R2-EVO. Junos OS is unaffected by this vulnerability.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.50%

39.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Juniper	Junos Os Evolved	19.2	R1
Juniper	Junos Os Evolved	19.3	R2
Juniper	Junos Os Evolved	19.4	R1
Juniper	Junos Os Evolved	20.1	R1

References

https://kb.juniper.net/JSA11078Vendor Advisory
https://kb.juniper.net/JSA11078Vendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2020-1681?

Receipt of a specifically malformed NDP packet sent from the local area network (LAN) to a device running Juniper Networks Junos OS Evolved can cause the ndp process to crash, resulting in a Denial of Service (DoS). The process automatically restarts without intervention, but a continuous receipt of the malformed NDP packets could leaded to an extended Denial of Service condition. During this time, IPv6 neighbor learning will be affected. The issue occurs when parsing the incoming malformed NDP packet. Rather than simply discarding the packet, the process asserts, performing a controlled exit and restart, thereby avoiding any chance of an unhandled exception. Exploitation of this vulnerability is limited to a temporary denial of service, and cannot be leveraged to cause additional impact on the system. This issue is limited to the processing of IPv6 NDP packets. IPv4 packet processing cannot trigger, and is unaffected by this vulnerability. This issue affects all Juniper Networks Junos OS Evolved versions prior to 20.1R2-EVO. Junos OS is unaffected by this vulnerability.

How severe is CVE-2020-1681?

CVE-2020-1681 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.50% probability of exploitation in the next 30 days.

How do I fix CVE-2020-1681?

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.