CVE-2021-0267

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

MEDIUM

6.5

CVSS Score

Published: April 22, 2021 at 07:37 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

1 product affected across 1 vendorJunos

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Severity

MEDIUM6.5

Exploit prediction

EPSS 0.5%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos · Juniper Networks

95%

19.4 ≤ v < 19.4R3-S120.1 ≤ v < 20.1R2-S1, 20.1R320.2 ≤ v < 20.2R320.3 ≤ v < 20.3R219.4 19.4 r1 19.4 r1-s1 19.4 r1-s2 19.4 r2 19.4 r2-s1 19.4 r2-s2 19.4 r3 20.1 20.1 r1 20.1 r1-s1 20.1 r1-s2 20.1 r1-s3 20.1 r1-s4 20.1 r2 20.2 20.2 r1 20.2 r1-s1 20.2 r1-s2 20.2 r1-s3 20.2 r2 20.2 r2-s1 20.2 r2-s2 20.2 r2-s3 20.3 20.3 r1 20.3 r1-s1

Affected range stops below 19.4R3-S1, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2-S1, 20.1R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R3, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_MISCVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11158

x_refsource_MISCVendor Advisory

Source: [email protected]

https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/ref/statement/active-leasequery-edit-forwarding-options.html

CVSS

6.5MEDIUM[email protected]

Attack Vector: ADJACENT_NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-20

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