PT-2025-15845 · Juniper Networks · Junos

Published 2025-04-09 · Updated 2025-04-11 · CVE-2025-21594

Positive Technologies (AI Summary)

CVSS v4.0

8.7

High

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:U/V:X/RE:X/U:X

Name of the Vulnerable Software and Affected Versions: Junos OS versions 21.2 through 21.2R3-S8 Junos OS versions 21.4 through 21.4R3-S7 Junos OS versions 22.1 through 22.1R3-S6 Junos OS versions 22.2 through 22.2R3-S4 Junos OS versions 22.3 through 22.3R3-S3 Junos OS versions 22.4 through 22.4R3-S2 Junos OS versions 23.2 through 23.2R2-S1 Junos OS versions 23.4 through 23.4R1-S2, 23.4R2

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 the 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. The issue can be identified using the command show services nat source port-block.

Recommendations: For Junos OS versions 21.2 through 21.2R3-S8, update to version 21.2R3-S8 or later. For Junos OS versions 21.4 through 21.4R3-S7, update to version 21.4R3-S7 or later. For Junos OS versions 22.1 through 22.1R3-S6, update to version 22.1R3-S6 or later. For Junos OS versions 22.2 through 22.2R3-S4, update to version 22.2R3-S4 or later. For Junos OS versions 22.3 through 22.3R3-S3, update to version 22.3R3-S3 or later. For Junos OS versions 22.4 through 22.4R3-S2, update to version 22.4R3-S2 or later. For Junos OS versions 23.2 through 23.2R2-S1, update to version 23.2R2-S1 or later. For Junos OS versions 23.4 through 23.4R1-S2, 23.4R2, update to a version later than 23.4R2. As a temporary workaround, consider manually restarting the affected FPC/PIC to recover from the Denial of Service (DoS) condition.

Fix

DoS

Improper Check for Exceptional Conditions

Weakness Enumeration

CWE-754

Related Identifiers

BDU:2025-08111

CVE-2025-21594

Affected Products

Junos

References · 9

• https://nvd.nist.gov/vuln/detail/CVE-2025-21594 · Security Note
• https://supportportal.juniper.net/JSA96449 · Vendor Advisory
• https://bdu.fstec.ru/vul/2025-08111 · Security Note
• https://osv.dev/vulnerability/CVE-2025-21594 · Vendor Advisory
• https://twitter.com/vulns_space/status/1910067634093085080 · Twitter Post
• https://twitter.com/cybercronai/status/1910535891870687384 · Twitter Post
• https://t.me/cvenotify/118888 · Telegram Post
• https://twitter.com/vuldb/status/1910068973749846165 · Twitter Post
• https://twitter.com/CVEnew/status/1910073385368891547 · Twitter Post