What’s Vulnerable › Vulnerabilities

CVE-2021-0267: Junos OS: Receipt of a crafted DHCP packet will cause the jdhcpd DHCP service to core.

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-22 · updated 2026-06-17
• Weakness: CWE-20

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 products

• Juniper Junos OS: 19.4-r1, 19.4-r1-s1, 19.4-r1-s2, 19.4-r2, 19.4-r2-s1, 19.4-r2-s2 (+17)

References

• https://kb.juniper.net/JSA11158
• https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/ref/statement/active-leasequery-edit-forwarding-options.html
• https://kb.juniper.net/JSA11158
• https://www.juniper.net/documentation/us/en/software/junos/subscriber-mgmt-sessions/topics/ref/statement/active-leasequery-edit-forwarding-options.html

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