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

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Summary

CVECVE-2026-33781
StatePUBLISHED
Assignerjuniper
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-09 22:16:27 UTC
Updated2026-04-17 17:53:32 UTC
DescriptionAn 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.

Risk And Classification

Primary CVSS: v4.0 7.1 HIGH from [email protected]

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/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

EPSS: 0.000200000 probability, percentile 0.051620000 (date 2026-04-18)

Problem Types: CWE-754 | CWE-754 CWE-754 Improper Check for Unusual or Exceptional Conditions

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary7.1HIGHCVSS: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/C...
4.0CNACVSS7.1HIGHCVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/...
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v4.0 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
Low

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/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

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Hardware Juniper Ex4000 - All All All
Hardware Juniper Ex4100 - All All All
Hardware Juniper Ex4100-f - All All All
Hardware Juniper Ex4100-h - All All All
Hardware Juniper Ex4300 - All All All
Hardware Juniper Ex4400 - All All All
Hardware Juniper Ex4600 - All All All
Hardware Juniper Ex4650 - All All All
Operating System Juniper Junos 24.4 - All All
Operating System Juniper Junos 24.4 r1 All All
Operating System Juniper Junos 24.4 r1-s2 All All
Operating System Juniper Junos 24.4 r1-s3 All All
Operating System Juniper Junos 25.2 - All All
Operating System Juniper Junos 25.2 r1 All All
Operating System Juniper Junos 25.2 r2 All All
Hardware Juniper Qfx5110 - All All All
Hardware Juniper Qfx5120 - All All All
Hardware Juniper Qfx5130 - All All All
Hardware Juniper Qfx5200 - All All All
Hardware Juniper Qfx5210 - All All All
Hardware Juniper Qfx5220 - All All All
Hardware Juniper Qfx5230-64cd - All All All
Hardware Juniper Qfx5240 - All All All
Hardware Juniper Qfx5241 - All All All
Hardware Juniper Qfx5700 - All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Juniper Networks Junos OS affected 24.4 24.4R2 semver EX Series, QFX Series
CNA Juniper Networks Junos OS affected 25.2 25.2R1-S1, 25.2R2 semver EX Series, QFX Series
CNA Juniper Networks Junos OS unaffected 24.4R1 semver EX Series, QFX Series

References

ReferenceSourceLinkTags
kb.juniper.net/JSA107869 [email protected] kb.juniper.net Mitigation, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

CNA: 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.

Workarounds

CNA: To prevent VSTP BPDUs from being processed on UNI interfaces configure: [ protocols layer2-control bpdu-block interface all drop ]

Exploits

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

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