CVE-2021-0222

Traffic interruption via invalid-packet replication

Published Jan 15, 2021 · Updated Sep 16, 2024

Denial of service in Juniper Networks Junos OS on affected EX and QFX switches allows attackers to interrupt traffic. Invalid IPv4 or IPv6 protocol payloads that should be discarded are instead duplicated, forwarded to the Routing Engine, and accumulated until service fails. Exploitation requires sustained crafted traffic from an adjacent device; continued receipt extends the outage and can disrupt wider traffic through protocol flapping.

CVSS severity7.4
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Juniper Networks Junos OS on affected EX and QFX switches allows attackers to interrupt traffic. Invalid IPv4 or IPv6 protocol payloads that should be discarded are instead duplicated, forwarded to the Routing Engine, and accumulated until service fails. Exploitation requires sustained crafted traffic from an adjacent device; continued receipt extends the outage and can disrupt wider traffic through protocol flapping.

The record

CVE
CVE-2021-0222
Published
Jan 15, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-16, T1499.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=14.1X53 <14.1X53-D53
  2. Affected versionversion=15.1 <15.1R7-S6
  3. Affected versionversion=16.1 <16.1R7-S7
  4. Affected versionversion=17.1 <17.1R2-S11
  5. Affected versionversion=17.1 <17.1R3-S2
  6. Affected versionversion=17.2 <17.2R1-S9
  7. Affected versionversion=17.2 <17.2R3-S3
  8. Affected versionversion=17.3 <17.3R2-S5, 17.3R3-S7
  9. Affected versionversion=17.4 <17.4R2-S9, 17.4R3
  10. Affected versionversion=18.1 <18.1R3-S9
  11. Affected versionversion=18.2 <18.2R2-S7
  12. Affected versionversion=18.2 <18.2R3-S3
  13. Affected versionversion=18.3 <18.3R1-S7, 18.3R3-S1
  14. Affected versionversion=18.3 <18.3R2-S3
  15. Affected versionversion=18.4 <18.4R1-S5, 18.4R2-S3, 18.4R3
  16. Affected versionversion=19.1 <19.1R1-S4, 19.1R2-S1, 19.1R3
  17. Affected versionversion=19.2 <19.2R1-S3, 19.2R2
  18. Affected versionversion=19.2 <19.2R1-S4, 19.2R2
  19. Affected versionversion=19.3 <19.3R1-S1, 19.3R2, 19.3R3
  20. Affected versionversion=19.3 <19.3R2-S1, 19.3R3

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=14.1X53 <14.1X53-D53; version=15.1 <15.1R7-S6; version=16.1 <16.1R7-S7; version=17.1 <17.1R2-S11; version=17.1 <17.1R3-S2; version=17.2 <17.2R1-S9; version=17.2 <17.2R3-S3; version=17.3 <17.3R2-S5, 17.3R3-S7; version=17.4 <17.4R2-S9, 17.4R3; version=18.1 <18.1R3-S9; version=18.2 <18.2R2-S7; version=18.2 <18.2R3-S3; version=18.3 <18.3R1-S7, 18.3R3-S1; version=18.3 <18.3R2-S3; version=18.4 <18.4R1-S5, 18.4R2-S3, 18.4R3; version=19.1 <19.1R1-S4, 19.1R2-S1, 19.1R3; version=19.2 <19.2R1-S3, 19.2R2; version=19.2 <19.2R1-S4, 19.2R2; version=19.3 <19.3R1-S1, 19.3R2, 19.3R3; version=19.3 <19.3R2-S1, 19.3R3

Published CVSS scores

7.4Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
6.1NIST NVDAV:A/AC:L/Au:N/C:N/I:N/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-16Configuration
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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