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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 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.


Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.5, indicating it requires adjacent network access with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 19 products from juniper, from juniper, from juniper and 16 others, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2026-04-09T22:16:27.193

Last Modified

2026-06-17T10:38:05.487

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 6.5 (MEDIUM)

Weaknesses
  • Type: Secondary
    CWE-754

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 24.4 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Operating System juniper junos 25.2 Yes
Hardware juniper ex4000 - No
Hardware juniper ex4100 - No
Hardware juniper ex4100-f - No
Hardware juniper ex4100-h - No
Hardware juniper ex4300 - No
Hardware juniper ex4400 - No
Hardware juniper ex4600 - No
Hardware juniper ex4650 - No
Hardware juniper qfx5110 - No
Hardware juniper qfx5120 - No
Hardware juniper qfx5130 - No
Hardware juniper qfx5200 - No
Hardware juniper qfx5210 - No
Hardware juniper qfx5220 - No
Hardware juniper qfx5230-64cd - No
Hardware juniper qfx5240 - No
Hardware juniper qfx5241 - No
Hardware juniper qfx5700 - No

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.