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TI-2021-00173 Aliases CVE-2021-0239GHSA-hr3q-mvqf-hmmc

Junos OS Evolved: Denial of Service due to receipt of specific genuine layer 2 frames.

Priority LOW 29CWE-754Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA.

Summary

In Juniper Networks Junos OS Evolved, receipt of a stream of specific genuine Layer 2 frames may cause the Advanced Forwarding Toolkit (AFT) manager process (Evo-aftmand), responsible for handling Route, Class-of-Service (CoS), Firewall operations within the packet forwarding engine (PFE) to crash and restart, leading to a Denial of Service (DoS) condition. By continuously sending this specific stream of genuine Layer 2 frames, an attacker can repeatedly crash the PFE, causing a sustained Denial of Service (DoS). This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R1-EVO. This issue does not affect Junos OS versions.

Why it matters now

EPSS 0.00381 32nd percentileScored 2026-11-07
Fix Fixed Junos OS Evolved (Juniper Networks): 20.4R1-EVO

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
JuniperJunos OS Evolvedbefore 20.4R1-EVO20.4R1-EVOPatch availableCNA
  • Junos OS Evolved VendorJuniper Affected before 20.4R1-EVO Fixed in 20.4R1-EVO Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:o:juniper:junos_os_evolved:20.4:r1:*:*:*:*:*:*20.4 r1VulnerableJuniper
  • cpe:2.3:o:juniper:junos_os_evolved:20.4:r1:*:*:*:*:*:* Versions 20.4 r1 Vulnerable ·Juniper

Remediation

  • Fix · CNA Junos OS Evolved (Juniper Networks) Fixed in 20.4R1-EVO

Timeline

  1. 2026-10-02 Threatist record created from CVE-2021-0239
  2. 2026-10-03 Alias added: GHSA-hr3q-mvqf-hmmc

References

Advisory 1

  • TI-2026-17602 Junos OS Evolved: PTX Series: A vulnerability allows a unauthenticated, network-based attacker to execute code as root CVSS 4.0CRITICAL 9.3
  • TI-2026-17601 Junos OS and Junos OS Evolved: Configuration of a specific SSH option results in mgd crash CVSS 4.0MEDIUM 6.7
  • TI-2023-04136 Improper input validation in Juniper Junos OS CVSS 3.1HIGH 7.5
  • TI-2026-74215 Stack-based buffer overflow in Junos OS rpd triggered by BGP peers CVSS 4.0CRITICAL 9.3
  • TI-2026-74211 Authentication bypass in Juniper J-Web allows pre-auth CGI execution CVSS 4.0CRITICAL 9.3
  • TI-2021-00146 Junos OS and Junos OS Evolved: Upon receipt of a specific BGP FlowSpec message network traffic may be disrupted. CVSS 3.1CRITICAL 10.0
See all 249 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences