CVE-2025-21591: Junos OS: An unauthenticated adjacent attacker sending a malformed DHCP packet causes jdhcpd to crash
A Buffer Access with Incorrect Length Value vulnerability in the jdhcpd daemon of Juniper Networks Junos OS, when DHCP snooping is enabled, allows an unauthenticated, adjacent, attacker to send a DHCP packet with a malformed DHCP option to cause jdhcp to crash creating a Denial of Service (DoS) condition.
Continuous receipt of these DHCP packets using the malformed DHCP Option will create a sustained Denial of Service (DoS) condition.
This issue affects Junos OS:
from 23.1 before 23.2R2-S3, from 23.4 before 23.4R2-S3, from 24.2 before 24.2R2.
This issue isn't applicable to any versions of Junos OS before 23.1R1.
This issue doesn't affect vSRX Series which doesn't support DHCP Snooping.
This issue doesn't affect Junos OS Evolved.
There are no indicators of compromise for this issue.
Affected Software
Remediation
Information
Event History
Frequently Asked Questions
What is the severity of CVE-2025-21591?
CVE-2025-21591 is classified as a high severity vulnerability due to its potential to cause Denial of Service.
How do I fix CVE-2025-21591?
To resolve CVE-2025-21591, it is recommended to update the Junos OS to a version that addresses this vulnerability.
Who is affected by CVE-2025-21591?
CVE-2025-21591 affects Juniper Networks Junos OS versions between 23.1R1 and 24.2R2, specifically with DHCP snooping enabled.
What type of vulnerability is CVE-2025-21591?
CVE-2025-21591 is a Buffer Access with Incorrect Length Value vulnerability that allows attackers to crash the jdhcp daemon.
What could happen if CVE-2025-21591 is exploited?
Exploitation of CVE-2025-21591 could lead to a denial of service, causing the jdhcp daemon to crash.