Juniper Junos OS jdhcpd DoS via Option82 (pre21.2R3, fixed in 21.4R3)
CVE-2025-59960 Published on January 15, 2026
Junos OS and Junos OS Evolved: DHCP Option 82 messages from clients being passed unmodified to the DHCP server
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Juniper DHCP service (jdhcpd) of Juniper Networks Junos OS and Junos OS Evolved allows a DHCP client in one subnet to exhaust the address pools of other subnets, leading to a Denial of Service (DoS) on the downstream DHCP server.
By default, the DHCP relay agent inserts its own Option 82 information when forwarding client requests, optionally replacing any Option 82 information provided by the client. When a specific DHCP DISCOVER is received in 'forward-only' mode with Option 82, the device should drop the message unless 'trust-option82' is configured. Instead, the DHCP relay forwards these packets to the DHCP server unmodified, which uses up addresses in the DHCP server's address pool, ultimately leading to address pool exhaustion.
This issue affects Junos OS:
* all versions before 21.2R3-S10,
* from 21.4 before 21.4R3-S12,
* all versions of 22.2,
* from 22.4 before 22.4R3-S8,
* from 23.2 before 23.2R2-S5,
* from 23.4 before 23.4R2-S6,
* from 24.2 before 24.2R2-S2,
* from 24.4 before 24.4R2,
* from 25.2 before 25.2R1-S1, 25.2R2.
Junos OS Evolved:
* all versions before 21.4R3-S12-EVO,
* all versions of 22.2-EVO,
* from 22.4 before 22.4R3-S8-EVO,
* from 23.2 before 23.2R2-S5-EVO,
* from 23.4 before 23.4R2-S6-EVO,
* from 24.2 before 24.2R2-S2-EVO,
* from 24.4 before 24.4R2-EVO,
* from 25.2 before 25.2R1-S1-EVO, 25.2R2-EVO.
Vulnerability Analysis
Timeline
Initial Publication
Weakness Type
Improper Check for Unusual or Exceptional Conditions
The software does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the software.
Products Associated with CVE-2025-59960
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Affected Versions
Juniper Networks Junos OS:- Before 21.2R3-S10 is affected.
- Version 21.4 and below 21.4R3-S12 is affected.
- Version 22.2 and below 22.2* is affected.
- Version 22.4 and below 22.4R3-S8 is affected.
- Version 23.2 and below 23.2R2-S5 is affected.
- Version 23.4 and below 23.4R2-S6 is affected.
- Version 24.2 and below 24.2R2-S2 is affected.
- Version 24.4 and below 24.4R2 is affected.
- Version 25.2 and below 25.2R1-S1, 25.2R2 is affected.
- Before 21.4R3-S12-EVO is affected.
- Version 22.2 and below 22.2* is affected.
- Version 22.4 and below 22.4R3-S8-EVO is affected.
- Version 23.2 and below 23.2R2-S5-EVO is affected.
- Version 23.4 and below 23.4R2-S6-EVO is affected.
- Version 24.2 and below 24.2R2-S2-EVO is affected.
- Version 24.4 and below 24.4R2-EVO is affected.
- Version 25.2 and below 25.2R1-S1-EVO, 25.2R2-EVO is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.