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Vulnerabilities/CVE-2026-33781Public Intelligence Dossier
Source: juniper · Limited verification•Last verified: •Collection Degraded
CVE-2026-33781Unknown / EvaluatingHIGH (raw)CVSS 7.1CWE-754

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)

Published: 10 Apr 2026•Last updated: 27 Oct 2026, 03:40 AM IST•Source identifier: sirt@juniper.net
Dossier completeness: source-provided sections 2 / 3 · rule guidance not available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Unknown
KEV status was not determined.
CVSS score
7.1HIGH (raw)
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
Metric sourcesirt@juniper.net
EPSS probability
0.2%0.002
Percentile6th
Weakness type
CWE-754
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

High

Actively exploited (source statement)

Unknown

Publicly disclosed

Unknown

Risk basis: Microsoft or Microsoft-managed product relevance; HIGH severity; Source severity; no confirmed exploitation signal

Affected Products & Remediation

1 source-backed product
Affected products and versions (source)
  • juniper junos · 24.4; 25.2 · NVD CPE · Source
NVD applicability prerequisites: cpe:2.3:h:juniper:ex4000:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4100:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4100-f:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4100-h:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4300:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4400:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4600:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4650:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:qfx5110:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:qfx5120:-:*:*:*:*:*:*:*. These are conditions, not proof that an environment is exposed or unaffected.
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

Not provided by source

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Unknown
Exploited (source statement)
Unknown
Publicly disclosed (source)
Unknown

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

No rule-based guidance for this vulnerability class

CISA KEV Record

CISA KEV status was not determined for this record.

Change History & Source Data

— No recorded material change

CNA / source
sirt@juniper.net
Record status · verification
UPDATED · NVD API
CPE
cpe:2.3:o:juniper:junos:24.4:-:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:24.4:r1:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:24.4:r1-s2:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:24.4:r1-s3:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:25.2:-:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:25.2:r1:*:*:*:*:*:*, cpe:2.3:o:juniper:junos:25.2:r2:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4000:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4100:-:*:*:*:*:*:*:*, cpe:2.3:h:juniper:ex4100-f:-:*:*:*:*:*:*:*

Evidence & Provenance

2 public sources
kb.juniper.netSource recordnvd.nist.govSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2026-33781
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2026-33781
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2026-33781"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
Open KQL Library

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Correlated briefings

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.