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Description

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.

PUBLISHED Reserved 2024-12-26 | Published 2025-04-09 | Updated 2025-04-10 | Assigner juniper




HIGH: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

HIGH: 8.7CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/R:U

Problem types

CWE-754: Improper Check for Unusual or Exceptional Conditions

Product status

Default status
unaffected

Any version before 21.2R3-S8
affected

21.4 (semver) before 21.4R3-S7
affected

22.1 (semver) before 22.1R3-S6
affected

22.2 (semver) before 22.2R3-S4
affected

22.3 (semver) before 22.3R3-S3
affected

22.4 (semver) before 22.4R3-S2
affected

23.2 (semver) before 23.2R2-S1
affected

23.4 (semver) before 23.4R1-S2, 23.4R2
affected

Any version before 20.2R1
unaffected

Timeline

2025-04-09:Initial Publication

References

supportportal.juniper.net/JSA96449 vendor-advisory

cve.org (CVE-2025-21594)

nvd.nist.gov (CVE-2025-21594)

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