CVE-2021-0233: Junos OS: ACX500 Series, ACX4000 Series: Denial of Service due to FFEB crash while processing high rate of specific packets.

Severity: medium (CVSS 5.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-04-22 · updated 2026-06-17
Weakness: CWE-400

Description

A vulnerability in Juniper Networks Junos OS ACX500 Series, ACX4000 Series, may allow an attacker to cause a Denial of Service (DoS) by sending a high rate of specific packets to the device, resulting in a Forwarding Engine Board (FFEB) crash. Continued receipt of these packets will sustain the Denial of Service (DoS) condition. This issue affects Juniper Networks Junos OS on ACX500 Series, ACX4000 Series: 17.4 versions prior to 17.4R3-S2.

Affected products

Juniper Junos OS: 17.4, 17.4-r1, 17.4-r1-s1, 17.4-r1-s2, 17.4-r1-s3, 17.4-r1-s4 (+17)

References

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