CVE-2026-57027CWE-401

Junos OS: EX4100 Series, EX4400: With sFlow configured in a VC scenario multicast traffic leads to an FPC crash

High · published July 9, 2026

CVSS v4.0
7.1
EPSS
0%
Percentile
18.1
In the wild
Unconfirmed
What it is

A Missing Release of Memory after Effective Lifetime vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX Series devices allows an unauthenticated adjacent attacker to cause a Denial-of-Service (DoS).When sFlow is configured in a Virtual Chassis (VC) scenario with EX4100 Series or EX4400 Series devices, multicast traffic which is received on one VC member and sent out on another member leads to a memory leak and ultimately an FPC crash and restart.

The leak can be monitored by watching the continuous increase of the buffer values in the output of:

user@host> show chassis fpc

This issue affects Junos OS on EX4100 Series and EX4400:

* all versions before 23.2R2-S7,

* 23.4 versions before 23.4R2-S7,

* 24.2 versions before 24.2R2-S4,

* 24.4 versions before 24.4R2.

The record
Technical detail
CVSS v4.0
7.1 · HIGH
Vector
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M
EPSS
0.00269 · 18.1th percentile
Weakness
CWE-401 · Missing Release of Memory after Effective Lifetime
Published
2026-07-09T21:08Z
EPSS history
Timeline
  • 09 JUL 21:08Z
    Junos OS: EX4100 Series, EX4400: With sFlow configured in a VC scenario multicast traffic leads to an FPC crash
    cvelistv5