CVE-2021-0295

Service interruption via DVMRP forwarding loop

Published Jul 15, 2021 · Updated Sep 17, 2024

Denial of service in Juniper Networks Junos OS on QFX10K Series switches allows attackers to interrupt forwarding via DVMRP packets. A DVMRP packet received on a multihomed ESI is sent to its peer and incorrectly forwarded through the same ESI, violating split horizon. The condition requires VXLAN with a multihomed ESI on QFX10002, QFX10008, or QFX10016 hardware; other platforms are unaffected.

CVSS severity6.1
Medium
EPSS probability1.10%
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 QFX10K Series switches allows attackers to interrupt forwarding via DVMRP packets. A DVMRP packet received on a multihomed ESI is sent to its peer and incorrectly forwarded through the same ESI, violating split horizon. The condition requires VXLAN with a multihomed ESI on QFX10002, QFX10008, or QFX10016 hardware; other platforms are unaffected.

The record

CVE
CVE-2021-0295
Published
Jul 15, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-697, T1498
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=17.3 <17.3R3-S12
  2. Affected versionversion=17.4 <17.4R3-S5
  3. Affected versionversion=18.1 <18.1R3-S13
  4. Affected versionversion=18.2R1 <18.2*
  5. Affected versionversion=18.3 <18.3R3-S5
  6. Affected versionversion=18.4 <18.4R2-S9, 18.4R3-S8
  7. Affected versionversion=19.1 <19.1R3-S5
  8. Affected versionversion=19.2 <19.2R1-S7, 19.2R3-S2
  9. Affected versionversion=19.3 <19.3R3-S2
  10. Affected versionversion=19.4 <19.4R3-S3
  11. Affected versionversion=20.1 <20.1R2-S2, 20.1R3
  12. Affected versionversion=20.2 <20.2R3
  13. Affected versionversion=20.3 <20.3R3
  14. Affected versionversion=20.4 <20.4R2

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=17.3 <17.3R3-S12; version=17.4 <17.4R3-S5; version=18.1 <18.1R3-S13; version=18.2R1 <18.2*; version=18.3 <18.3R3-S5; version=18.4 <18.4R2-S9, 18.4R3-S8; version=19.1 <19.1R3-S5; version=19.2 <19.2R1-S7, 19.2R3-S2; version=19.3 <19.3R3-S2; version=19.4 <19.4R3-S3; version=20.1 <20.1R2-S2, 20.1R3; version=20.2 <20.2R3; version=20.3 <20.3R3; version=20.4 <20.4R2

Published CVSS scores

6.1Juniper NetworksCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:L
2.9NISTAV:A/AC:M/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-697Incorrect Comparison
T1498Network 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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