Junos OS: Receipt of a crafted DHCP packet will cause the jdhcpd DHCP service to core.

published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-2886

cvss: 7.4; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

Juniper Networks Junos OS 19.4R3-S1, 20.1R2-S1, 20.1R3, 20.2R3, 20.3R2

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.4	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD	3.1	6.5	CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	3.3	AV:A/AC:L/Au:N/C:N/I:N/A:P

Affected products

Juniper Networks Junos OS

Classification

Weakness

CWE-20 Improper Input Validation

References

kb.juniper.net /JSA11158
vendor-advisory
juniper.net /documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/ref/statement/active-leasequery-edit-forwa
vendor-advisory

Sources

CVE List CVE-2021-0267
NVD CVE-2021-0267

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Summary