CVE-2021-0283Network attack vector

Device shutdown via TCP/IP stack buffer overflow

Published Jul 15, 2021 · Updated Sep 17, 2024

Buffer overflow in the Junos OS TCP/IP stack allows remote attackers to shut down affected devices with crafted packet sequences. The stack processes specific packet sequences addressed to the device beyond a buffer boundary, crashing the kernel into an abnormal shutdown. Only device-destined traffic reaches the flaw; transit traffic does not, and repeated sequences sustain the service interruption.

CVSS severity7.5
High
EPSS probability0.99%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in the Junos OS TCP/IP stack allows remote attackers to shut down affected devices with crafted packet sequences. The stack processes specific packet sequences addressed to the device beyond a buffer boundary, crashing the kernel into an abnormal shutdown. Only device-destined traffic reaches the flaw; transit traffic does not, and repeated sequences sustain the service interruption.

The record

CVE
CVE-2021-0283
Published
Jul 15, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-120, T1499.004
Attack vector
network
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=12.3 <12.3R12-S19
  2. Affected versionversion=15.1 <15.1R7-S10
  3. Affected versionversion=16.1R1 <16.1*
  4. Affected versionversion=16.2R1 <16.2*
  5. Affected versionversion=17.1R1 <17.1*
  6. Affected versionversion=17.2R1 <17.2*
  7. Affected versionversion=17.3 <17.3R3-S12
  8. Affected versionversion=17.4R1 <17.4*
  9. Affected versionversion=18.1 <18.1R3-S13
  10. Affected versionversion=18.2R1 <18.2*
  11. Affected versionversion=18.3 <18.3R3-S5
  12. Affected versionversion=18.4 <18.4R2-S9, 18.4R3-S9
  13. Affected versionversion=19.1 <19.1R3-S6
  14. Affected versionversion=19.2 <19.2R1-S7, 19.2R3-S3
  15. Affected versionversion=19.3 <19.3R2-S7, 19.3R3-S3
  16. Affected versionversion=19.4 <19.4R3-S5
  17. Affected versionversion=20.1 <20.1R2-S2, 20.1R3-S1
  18. Affected versionversion=20.2 <20.2R3-S2
  19. Affected versionversion=20.3 <20.3R3
  20. Affected versionversion=20.4 <20.4R2-S1, 20.4R3
  21. Affected versionversion=21.1 <21.1R1-S1, 21.1R2
  22. Affected versionversion=21.2 <21.2R1-S1, 21.2R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos OSversion=12.3 <12.3R12-S19; version=15.1 <15.1R7-S10; version=16.1R1 <16.1*; version=16.2R1 <16.2*; version=17.1R1 <17.1*; version=17.2R1 <17.2*; version=17.3 <17.3R3-S12; version=17.4R1 <17.4*; 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-S9; version=19.1 <19.1R3-S6; version=19.2 <19.2R1-S7, 19.2R3-S3; version=19.3 <19.3R2-S7, 19.3R3-S3; version=19.4 <19.4R3-S5; version=20.1 <20.1R2-S2, 20.1R3-S1; version=20.2 <20.2R3-S2; version=20.3 <20.3R3; version=20.4 <20.4R2-S1, 20.4R3; version=21.1 <21.1R1-S1, 21.1R2; version=21.2 <21.2R1-S1, 21.2R2

Published CVSS scores

7.5Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499.004Application or System Exploitation

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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