CVE-2021-0226

Junos OS Evolved: The IPv6 BGP session will flap due to receipt of a specific IPv6 packet

HIGH

7.5

CVSS Score

Published: April 22, 2021 at 07:36 PM UTC

Updated: June 17, 2026 at 03:29 AM UTC

2 products affected across 2 vendorsJunos OS EvolvedJunos OS Evolved

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Severity

HIGH7.5

Exploit prediction

EPSS 0.9%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Junos OS Evolved · Juniper

95%

20.1 r1 20.1 r1-s1 20.1 r2 20.1 r2-s1 20.1 r2-s2 20.2 r1 20.2 r1-s1 20.2 r2 20.3 r1 20.3 r1-s1

Junos OS Evolved · Juniper Networks

60%

19.4-EVO ≤ v < 19.4R2-S3-EVO20.1-EVO ≤ v < 20.1R2-S3-EVO20.2-EVO ≤ v < 20.2R2-S1-EVO20.3-EVO ≤ v < 20.3R2-EVO19.4-EVO 20.1-EVO 20.2-EVO 20.3-EVO

Affected range stops below 19.4R2-S3-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.1R2-S3-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.2R2-S1-EVO, so it looks safe — our inference, not a vendor statement

Affected range stops below 20.3R2-EVO, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://kb.juniper.net/JSA11121

References (1)

x_refsource_MISCVendor Advisory

Source: [email protected]

https://kb.juniper.net/JSA11121

CVSS

7.5HIGH[email protected]

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-665

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