CVE-2020-1641: A Race Condition vulnerability in Juniper Networks Junos OS LLDP implementation allows an attacker to cause LLDP to crash leading to a Denial of Servi...

Description

A Race Condition vulnerability in Juniper Networks Junos OS LLDP implementation allows an attacker to cause LLDP to crash leading to a Denial of Service (DoS). This issue occurs when crafted LLDP packets are received by the device from an adjacent device. Multiple LACP flaps will occur after LLDP crashes. An indicator of compromise is to evaluate log file details for lldp with RLIMIT. Intervention should occur before 85% threshold of used KB versus maximum available KB memory is reached. show log messages | match RLIMIT | match lldp | last 20 Matching statement is " /kernel: %KERNEL-[number]: Process ([pid #],lldpd) has exceeded 85% of RLIMIT_DATA: " with [] as variable data to evaluate for. This issue affects: Juniper Networks Junos OS: 12.3 versions prior to 12.3R12-S15; 12.3X48 versions prior to 12.3X48-D95; 15.1 versions prior to 15.1R7-S6; 15.1X49 versions prior to 15.1X49-D200; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S7; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2; 17.2 versions prior to 17.2R1-S9, 17.2R3-S3; 17.3 versions prior to 17.3R2-S5, 17.3R3-S6; 17.4 versions prior to 17.4R2-S4, 17.4R3; 18.1 versions prior to 18.1R3-S5; 18.2 versions prior to 18.2R2-S7, 18.2R3; 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D33, 18.2X75-D50, 18.2X75-D420; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3; 18.4 versions prior to 18.4R1-S5, 18.4R2; 19.1 versions prior to 19.1R1-S4, 19.1R2.

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

0.38%

30.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Juniper	Junos	12.3
Juniper	Junos	12.3x48
Juniper	Junos	15.1
Juniper	Junos	15.1x49
Juniper	Junos	15.1x53
Juniper	Junos	16.1
Juniper	Junos	17.1
Juniper	Junos	17.2
Juniper	Junos	17.3
Juniper	Junos	17.4
Juniper	Junos	18.1
Juniper	Junos	18.2
Juniper	Junos	18.2x75
Juniper	Junos	18.3
Juniper	Junos	18.4
Juniper	Junos	19.1

References

https://kb.juniper.net/JSA11027Vendor Advisory
https://kb.juniper.net/JSA11027Vendor Advisory

Timeline

Published: Jul 17, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-1641?

A Race Condition vulnerability in Juniper Networks Junos OS LLDP implementation allows an attacker to cause LLDP to crash leading to a Denial of Service (DoS). This issue occurs when crafted LLDP packets are received by the device from an adjacent device. Multiple LACP flaps will occur after LLDP crashes. An indicator of compromise is to evaluate log file details for lldp with RLIMIT. Intervention should occur before 85% threshold of used KB versus maximum available KB memory is reached. show log messages | match RLIMIT | match lldp | last 20 Matching statement is " /kernel: %KERNEL-[number]: Process ([pid #],lldpd) has exceeded 85% of RLIMIT_DATA: " with [] as variable data to evaluate for. This issue affects: Juniper Networks Junos OS: 12.3 versions prior to 12.3R12-S15; 12.3X48 versions prior to 12.3X48-D95; 15.1 versions prior to 15.1R7-S6; 15.1X49 versions prior to 15.1X49-D200; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S7; 17.1 versions prior to 17.1R2-S11, 17.1R3-S2; 17.2 versions prior to 17.2R1-S9, 17.2R3-S3; 17.3 versions prior to 17.3R2-S5, 17.3R3-S6; 17.4 versions prior to 17.4R2-S4, 17.4R3; 18.1 versions prior to 18.1R3-S5; 18.2 versions prior to 18.2R2-S7, 18.2R3; 18.2X75 versions prior to 18.2X75-D12, 18.2X75-D33, 18.2X75-D50, 18.2X75-D420; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3; 18.4 versions prior to 18.4R1-S5, 18.4R2; 19.1 versions prior to 19.1R1-S4, 19.1R2.

How severe is CVE-2020-1641?

CVE-2020-1641 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.38% probability of exploitation in the next 30 days.

How do I fix CVE-2020-1641?

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.