CVE-2026-21903CWE-121

Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash

High · published January 15, 2026

CVSS v4.0
7.1
EPSS
0%
Percentile
33.0
In the wild
Unconfirmed
What it is

A Stack-based Buffer Overflow vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS allows a network-based attacker, authenticated with low privileges to cause a Denial-of-Service (DoS).

Subscribing to telemetry sensors at scale causes all FPC connections to drop, resulting in an FPC crash and restart.

The issue was not seen when YANG packages for the specific sensors were installed.

This issue affects Junos OS:

* all versions before 22.4R3-S7,

* 23.2 version before 23.2R2-S4,

* 23.4 versions before 23.4R2.

The record
Technical detail
CVSS v4.0
7.1 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L
EPSS
0.00399 · 33.0th percentile
Weakness
CWE-121 · Stack-based Buffer Overflow
Published
2026-01-15T20:18Z
EPSS history
Timeline
  • 15 JAN 20:18Z
    Junos OS: Subscribing to telemetry sensors at scale causes all FPCs to crash
    cvelistv5