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.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 11 products from juniper, from juniper, from juniper and 8 others, organizations running these solutions should prioritize assessment and patching.
Reported in 2025, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2025-04-09T20:15:25.620
2026-01-26T19:36:10.717
Analyzed
CVSSv3.1: 7.5 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.2 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 21.4 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.1 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.2 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.3 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 22.4 | Yes |
| Operating System | juniper | junos | 23.2 | Yes |
| Operating System | juniper | junos | 23.2 | Yes |
| Operating System | juniper | junos | 23.2 | Yes |
| Operating System | juniper | junos | 23.2 | Yes |
| Operating System | juniper | junos | 23.2 | Yes |
| Operating System | juniper | junos | 23.4 | Yes |
| Operating System | juniper | junos | 23.4 | Yes |
| Operating System | juniper | junos | 23.4 | Yes |
| Operating System | juniper | junos | 23.4 | Yes |
| Hardware | juniper | mx10004 | - | No |
| Hardware | juniper | mx10008 | - | No |
| Hardware | juniper | mx2008 | - | No |
| Hardware | juniper | mx2010 | - | No |
| Hardware | juniper | mx2020 | - | No |
| Hardware | juniper | mx204 | - | No |
| Hardware | juniper | mx240 | - | No |
| Hardware | juniper | mx304 | - | No |
| Hardware | juniper | mx480 | - | No |
| Hardware | juniper | mx960 | - | No |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.