CVE-2021-0293

Kernel crash via repeated leaking CLI command

Published Jul 15, 2021 · Updated Sep 16, 2024

Resource exhaustion in Juniper Networks Junos OS 18.2 through 20.3 allows local users to crash the kernel by repeating a CLI command. The show system connections extensive path fails to release memory after netstat processes each invocation, with leakage increasing with the system's TCP connection count. Low-privileged CLI access is sufficient; continued execution exhausts memory, crashes the kernel, interrupts traffic, and sustains the service outage.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Juniper Networks Junos OS 18.2 through 20.3 allows local users to crash the kernel by repeating a CLI command. The show system connections extensive path fails to release memory after netstat processes each invocation, with leakage increasing with the system's TCP connection count. Low-privileged CLI access is sufficient; continued execution exhausts memory, crashes the kernel, interrupts traffic, and sustains the service outage.

The record

CVE
CVE-2021-0293
Published
Jul 15, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

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

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=18.2 <18.2R2-S8, 18.2R3-S7
  2. Affected versionversion=18.3 <18.3R3-S4
  3. Affected versionversion=18.4 <18.4R1-S8, 18.4R2-S6, 18.4R3-S7
  4. Affected versionversion=19.1 <19.1R1-S6, 19.1R2-S2, 19.1R3-S4
  5. Affected versionversion=19.2 <19.2R1-S6, 19.2R3-S2
  6. Affected versionversion=19.3 <19.3R2-S6, 19.3R3-S1
  7. Affected versionversion=19.4 <19.4R1-S4, 19.4R2-S3, 19.4R3-S1
  8. Affected versionversion=20.1 <20.1R2
  9. Affected versionversion=20.2 <20.2R2-S1, 20.2R3
  10. Affected versionversion=20.3 <20.3R1-S1, 20.3R2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=18.2 <18.2R2-S8, 18.2R3-S7; version=18.3 <18.3R3-S4; version=18.4 <18.4R1-S8, 18.4R2-S6, 18.4R3-S7; version=19.1 <19.1R1-S6, 19.1R2-S2, 19.1R3-S4; version=19.2 <19.2R1-S6, 19.2R3-S2; version=19.3 <19.3R2-S6, 19.3R3-S1; version=19.4 <19.4R1-S4, 19.4R2-S3, 19.4R3-S1; version=20.1 <20.1R2; version=20.2 <20.2R2-S1, 20.2R3; version=20.3 <20.3R1-S1, 20.3R2

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:P
5.5Juniper NetworksCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
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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