How severe is CVE-2021-0226?

CVE-2021-0226 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2021-0226 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-0226?

CVE-2021-0226 primarily affects Juniper Junos Os Evolved. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-0226?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-0226 published?

CVE-2021-0226 was published on 2021-04-22 and last updated on 2026-06-17.

CVE-2021-0226

CVE-2021-0226 is a high-severity vulnerability in Juniper Junos Os Evolved with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-665.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v2: 5.0
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-665
Affected product: Juniper Junos Os Evolved
Published: 2021-04-22
Last modified: 2026-06-17

Description

On Juniper Networks Junos OS Evolved devices, receipt of a specific IPv6 packet may cause an established IPv6 BGP session to terminate, creating a Denial of Service (DoS) condition. Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue does not affect IPv4 BGP sessions. This issue affects IBGP or EBGP peer sessions with IPv6. This issue affects: Juniper Networks Junos OS Evolved: 19.4 versions prior to 19.4R2-S3-EVO; 20.1 versions prior to 20.1R2-S3-EVO; 20.2 versions prior to 20.2R2-S1-EVO; 20.3 versions prior to 20.3R2-EVO. This issue does not affect Juniper Networks Junos OS releases.

Frequently asked questions

What is CVE-2021-0226?: On Juniper Networks Junos OS Evolved devices, receipt of a specific IPv6 packet may cause an established IPv6 BGP session to terminate, creating a Denial of Service (DoS) condition. Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition. This issue does not affect IPv4 BGP sessions. This issue affects IBGP or EBGP peer sessions with IPv6. This issue affects: Juniper Networks Junos OS Evolved: 19.4 versions prior to 19.4R2-S3-EVO; 20.1 versions prior to 20.1R2-S3-EVO; 20.2 versions prior to 20.2R2-S1-EVO; 20.3 versions prior to 20.3R2-EVO. This issue does not affect Juniper Networks Junos OS releases.
How severe is CVE-2021-0226?: CVE-2021-0226 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2021-0226 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-0226?: CVE-2021-0226 primarily affects Juniper Junos Os Evolved. In total, 10 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-0226?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-0226 published?: CVE-2021-0226 was published on 2021-04-22 and last updated on 2026-06-17.

References

https://kb.juniper.net/JSA11121

Affected products (10)

cpe:2.3:o:juniper:junos_os_evolved:20.1:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.1:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.1:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.1:r2-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.1:r2-s2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.2:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.2:r1-s1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.2:r2:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.3:r1:*:*:*:*:*:*
cpe:2.3:o:juniper:junos_os_evolved:20.3:r1-s1:*:*:*:*:*:*

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