CVE-2021-0267: An Improper Input Validation vulnerability in the active-lease query portion in JDHCPD's DHCP Relay Agent of Juniper Networks Junos OS allows an attac...

Description

An Improper Input Validation vulnerability in the active-lease query portion in JDHCPD's DHCP Relay Agent of Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) by sending a crafted DHCP packet to the device thereby crashing the jdhcpd DHCP service. This is typically configured for Broadband Subscriber Sessions. Continued receipt and processing of this crafted packet will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS: 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R2. This issue does not affect Junos OS Evolved.

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

0.47%

36.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions	Update
Juniper	Junos	19.4	R1
Juniper	Junos	20.1	R1
Juniper	Junos	20.2	R1
Juniper	Junos	20.3	R1

References

Timeline

Published: Apr 22, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-0267?

An Improper Input Validation vulnerability in the active-lease query portion in JDHCPD's DHCP Relay Agent of Juniper Networks Junos OS allows an attacker to cause a Denial of Service (DoS) by sending a crafted DHCP packet to the device thereby crashing the jdhcpd DHCP service. This is typically configured for Broadband Subscriber Sessions. Continued receipt and processing of this crafted packet will create a sustained Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS: 19.4 versions prior to 19.4R3-S1; 20.1 versions prior to 20.1R2-S1, 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R2. This issue does not affect Junos OS Evolved.

How severe is CVE-2021-0267?

CVE-2021-0267 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2021-0267?

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.