CVE-2021-0290

Adjacent-network DoS via exceptional Ethernet frame handling

Published Jul 15, 2021 · Updated Sep 16, 2024

Improper Ethernet frame handling in Juniper Networks Junos OS before fixed releases allows remote attackers on a local Ethernet segment to force interfaces down. The Ethernet frame-processing path mishandles exceptional crafted frames, leaving the affected interface permanently down until the forwarding-plane card is manually reset. An attacker needs adjacent-layer access to the segment; continued crafted-frame traffic sustains the denial of service, with no reported confidentiality or integrity impact.

CVSS severity6.5
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper Ethernet frame handling in Juniper Networks Junos OS before fixed releases allows remote attackers on a local Ethernet segment to force interfaces down. The Ethernet frame-processing path mishandles exceptional crafted frames, leaving the affected interface permanently down until the forwarding-plane card is manually reset. An attacker needs adjacent-layer access to the segment; continued crafted-frame traffic sustains the denial of service, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2021-0290
Published
Jul 15, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-755, T1499
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 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

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Is a vulnerable build present?

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

  1. Affected versionversion=16.1 <16.1R7-S7
  2. Affected versionversion=17.1R1 <17.1*
  3. Affected versionversion=17.2 <17.2R3-S3
  4. Affected versionversion=17.3 <17.3R3-S8
  5. Affected versionversion=17.4 <17.4R2-S11, 17.4R3-S1
  6. Affected versionversion=18.1 <18.1R3-S10
  7. Affected versionversion=18.2 <18.2R3-S3
  8. Affected versionversion=18.3 <18.3R3-S1
  9. Affected versionversion=18.4 <18.4R2-S3, 18.4R3
  10. Affected versionversion=19.1 <19.1R2-S1, 19.1R3
  11. Affected versionversion=19.2 <19.2R1-S3, 19.2R2
  12. Affected versionversion=19.3 <19.3R2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=16.1 <16.1R7-S7; version=17.1R1 <17.1*; version=17.2 <17.2R3-S3; version=17.3 <17.3R3-S8; version=17.4 <17.4R2-S11, 17.4R3-S1; version=18.1 <18.1R3-S10; version=18.2 <18.2R3-S3; version=18.3 <18.3R3-S1; version=18.4 <18.4R2-S3, 18.4R3; version=19.1 <19.1R2-S1, 19.1R3; version=19.2 <19.2R1-S3, 19.2R2; version=19.3 <19.3R2

Published CVSS scores

6.5Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.3NVDAV:A/AC:L/Au:N/C:N/I:N/A:P

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-755Improper Handling of Exceptional Conditions
T1499Endpoint Denial of Service

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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