An Improper Check for Unusual or Exceptional Conditions vulnerability in the pfe (packet forwarding engine) of Juniper Networks Junos OS on MX Series causes a port within a pool to be blocked leading to Denial of Service (DoS).
In a DS-Lite (Dual-Stack Lite) and NAT (Network Address Translation) scenario, when crafted IPv6 traffic is received and prefix-length is set to 56, the ports assigned to the user will not be freed. Eventually, users cannot establish new connections. Affected FPC/PIC need to be manually restarted to recover.
Following is the command to identify the issue:
user@host> show services nat source port-block
Host_IP External_IP Port_Block Ports_Used/ Block_State/
Range Ports_Total Left_Time(s)
2001:: x.x.x.x 58880-59391 256/256*1 Active/- >>>>>>>>port still usedThis issue affects Junos OS on MX Series:
* from 21.2 before 21.2R3-S8,
* from 21.4 before 21.4R3-S7,
* from 22.1 before 22.1R3-S6,
* from 22.2 before 22.2R3-S4,
* from 22.3 before 22.3R3-S3,
* from 22.4 before 22.4R3-S2,
* from 23.2 before 23.2R2-S1,
* from 23.4 before 23.4R1-S2, 23.4R2.
This issue does not affect versions before 20.2R1.
References
| Link | Resource |
|---|---|
| https://supportportal.juniper.net/JSA96449 | Vendor Advisory |
Configurations
Configuration 1 (hide)
| AND |
|
History
No history.
Information
Published : 2025-04-09 20:15
Updated : 2026-01-26 19:36
NVD link : CVE-2025-21594
Mitre link : CVE-2025-21594
CVE.ORG link : CVE-2025-21594
JSON object : View
Products Affected
juniper
- mx2010
- mx960
- mx2020
- mx304
- junos
- mx2008
- mx10008
- mx204
- mx480
- mx10004
- mx240
CWE
CWE-754
Improper Check for Unusual or Exceptional Conditions