CVE-2021-0238

Disk exhaustion via repeated CLI command

Published Apr 22, 2021 · Updated Sep 16, 2024

Resource exhaustion in Juniper Networks Junos OS on MX Series routers allows local users to exhaust disk space through a CLI command. On an L2TP-based BNG, repeated execution of the affected but publicly unnamed command consumes persistent storage until no free disk space remains. The condition requires low-privilege CLI access and the specific MX Series BNG configuration; Juniper has not disclosed the command or file-writing path.

CVSS severity5.5
Medium
EPSS probability0.23%
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 on MX Series routers allows local users to exhaust disk space through a CLI command. On an L2TP-based BNG, repeated execution of the affected but publicly unnamed command consumes persistent storage until no free disk space remains. The condition requires low-privilege CLI access and the specific MX Series BNG configuration; Juniper has not disclosed the command or file-writing path.

The record

CVE
CVE-2021-0238
Published
Apr 22, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-400, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 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=17.3R1 <17.3*
  2. Affected versionversion=17.4 <17.4R3-S5
  3. Affected versionversion=18.1 <18.1R3-S13
  4. Affected versionversion=18.2 <18.2R3-S7
  5. Affected versionversion=18.3 <18.3R3-S4
  6. Affected versionversion=18.4 <18.4R3-S7
  7. Affected versionversion=19.1 <19.1R3-S4
  8. Affected versionversion=19.2 <19.2R1-S6, 19.2R3-S2
  9. Affected versionversion=19.3 <19.3R3-S2
  10. Affected versionversion=19.4 <19.4R2-S4, 19.4R3-S2
  11. Affected versionversion=20.1 <20.1R3
  12. Affected versionversion=20.2 <20.2R2-S3, 20.2R3
  13. Affected versionversion=20.3 <20.3R2
  14. Affected versionversion=20.4 <20.4R1-S1, 20.4R2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=17.3R1 <17.3*; version=17.4 <17.4R3-S5; version=18.1 <18.1R3-S13; version=18.2 <18.2R3-S7; version=18.3 <18.3R3-S4; version=18.4 <18.4R3-S7; version=19.1 <19.1R3-S4; version=19.2 <19.2R1-S6, 19.2R3-S2; version=19.3 <19.3R3-S2; version=19.4 <19.4R2-S4, 19.4R3-S2; version=20.1 <20.1R3; version=20.2 <20.2R2-S3, 20.2R3; version=20.3 <20.3R2; version=20.4 <20.4R1-S1, 20.4R2

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-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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