CVE-2026-21903

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OS0 < 22.4R3-S7affected
Juniper NetworksJunos OS23.2 < 23.2R2-S4affected
Juniper NetworksJunos OS23.4 < 23.4R2affected

Weaknesses

  • CWE-121: CWE-121 Stack-based Buffer Overflow

Workarounds

There are no known workarounds for this issue.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References