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Vulnerabilities

Vulnerability · CVE-2021-0233

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…

Published Apr 22, 2021 · catalog updated Jun 17, 2026 · the affected product

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-0233. EPSS is 0.96%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.96%
Remediation
Advisory link
Affected products
cpe juniper/junos

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe juniper/junos17.4

How to fix CVE-2021-0233

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-0233. EPSS is 0.96%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with 17.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption; CWE-794. EPSS 0.96%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Juniper Junos OS security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 22, 2021 · Monitored products — high

    Detected

    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, ACX400

  2. Jun 17, 2026 · Monitored products — high

    Updated

    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, ACX400

Sources

  • CVE.orgVulnerability recordCVE-2021-0233

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2021-0233

    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, ACX400

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 7, 2026
  • Monitored products — highNov 7, 2026