CVE-2026-33781: 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…

PriorityP430medium6.5CVSS 3.1

AVAACLPRNUINSUCNINAH

EPSS

0.17%

6.1th percentile

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.

Affected

7 ranges

Vendor	Product	Version range	Fixed in
juniper	ex_series	—	—
juniper	junos	—	—
juniper	junos	—	—
juniper	junos_os	—	—
juniper	qfx_series	—	—
juniper_networks	junos_os	>= 24.4 < 24.4R2	24.4R2
juniper_networks	junos_os	>= 25.2 < 25.2R1-S1, 25.2R2	25.2R1-S1, 25.2R2

CVSS provenance

nvdv3.16.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvdv4.07.1HIGHCVSS:4.0/AV:A/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:Y/R:X/V:X/RE:M/U:X

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