CVE detail

CVE-2021-0239 — CVE-2021-0239

Published 2021-04-22 · Modified 2026-06-17 · Vendor juniper · Product junos_os_evolved · Source nvd

MEDIUM

severity

CVSS-derived band

6.5

CVSS v3

0–10 scale

0.0038

EPSS probability

exploitation probability, 30d

31.0%

EPSS percentile

percentile vs all CVEs

NOT LISTED

CISA KEV

known exploited catalog

Description

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.

Remediation

vendor remediation guidance

The following software releases have been updated to resolve this specific issue: Junos OS Evolved: 20.4R1-EVO, and all subsequent releases.

workarounds

There are no viable workarounds for this issue.

Product	Vulnerable range	Fixed version	Advisory
Juniper Networks Junos OS Evolved	>=unspecified<20.4R1-EVO	20.4R1-EVO	advisory ↗

References

cvedb.io · NVD · CISA KEV · FIRST EPSS · vendor advisories (CVE Program List v5). Informational only, no warranty — verify every remediation against the vendor advisory before acting on it. This product uses data from the NVD API but is not endorsed or certified by the NVD, CISA, FIRST.org or any vendor named. CVE® is a registered trademark of The MITRE Corporation.