CVE-2026-33781 PUBLISHED

Junos OS: EX Series, QFX Series: In a VXLAN scenario when specific control protocol packets are received, memory leaks and eventually no traffic is passed

Assigner: juniper
Reserved: 23.03.2026 Published: 09.04.2026 Updated: 10.04.2026

An Improper Check for Unusual or Exceptional Conditions vulnerability in the packet forwarding engine (pfe) of Juniper Networks Junos OS on specific EX and QFX Series devices allow an unauthenticated, adjacent attacker to cause a complete Denial of Service (DoS).

On EX4k, and QFX5k platforms configured as service-provider edge devices, if L2PT is enabled on the UNI and VSTP is enabled on NNI in VXLAN scenarios, receiving VSTP BPDUs on UNI leads to packet buffer allocation failures, resulting in the device to not pass traffic anymore until it is manually recovered with a restart.This issue affects Junos OS:

  • 24.4 releases before 24.4R2,
  • 25.2 releases before 25.2R1-S1, 25.2R2.

This issue does not affect Junos OS releases before 24.4R1.

Metrics

CVSS 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/RE:M
CVSS Score: 7.1

Product Status

Vendor Juniper Networks
Product Junos OS
Versions Default: unaffected
  • affected from 24.4 to 24.4R2 (excl.)
  • affected from 25.2 to 25.2R1-S1, 25.2R2 (excl.)
  • unaffected from 0 to 24.4R1 (excl.)

Exploits

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

Workarounds

To prevent VSTP BPDUs from being processed on UNI interfaces configure:

[ protocols layer2-control bpdu-block interface all drop ]

Solutions

The following software releases have been updated to resolve this specific issue: 24.4R2, 25.2R1-S1, 25.2R2, 25.4R1, and all subsequent releases.

References

Problem Types

  • CWE-754 Improper Check for Unusual or Exceptional Conditions CWE