CVE-2021-0238
Junos OS: MX Series: Executing CLI command repetitively may cause the system to run out of disk space
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling Protocol (L2TP), executing certain CLI command may cause the system to run out of disk space, excessive disk usage may cause other complications. An administrator can use the following CLI command to monitor the available disk space: user@device> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/gpt/junos 19G 18G 147M 99% /.mount <<<<< running out of space tmpfs 21G 16K 21G 0% /.mount/tmp tmpfs 5.3G 1.7M 5.3G 0% /.mount/mfs This issue affects Juniper Networks Junos OS on MX Series: 17.3R1 and later versions prior to 17.4R3-S5, 18.1 versions prior to 18.1R3-S13, 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2; This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Junos OS: MX Series: Executing CLI command repetitively may cause the system to run out of disk space
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling Protocol (L2TP), executing certain CLI command may cause the system to run out of disk space, excessive disk usage may cause other complications. An administrator can use the following CLI command to monitor the available disk space: user@device> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/gpt/junos 19G 18G 147M 99% /.mount <<<<< running out of space tmpfs 21G 16K 21G 0% /.mount/tmp tmpfs 5.3G 1.7M 5.3G 0% /.mount/mfs This issue affects Juniper Networks Junos OS on MX Series: 17.3R1 and later versions prior to 17.4R3-S5, 18.1 versions prior to 18.1R3-S13, 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2; This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.
- Record
CVE-2021-0238- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-400
- Updated
- 2026-11-02
EUVDEUVD-2021-2857
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling Protocol (L2TP), executing certain CLI command may cause the system to run out of disk space, excessive disk usage may cause other complications. An administrator can use the following CLI command to monitor the available disk space: user@device> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/gpt/junos 19G 18G 147M 99% /.mount <<<<< running out of space tmpfs 21G 16K 21G 0% /.mount/tmp tmpfs 5.3G 1.7M 5.3G 0% /.mount/mfs This issue affects Juniper Networks Junos OS on MX Series: 17.3R1 and later versions prior to 17.4R3-S5, 18.1 versions prior to 18.1R3-S13, 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2; This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.
- Record
EUVD-2021-2857- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-9f86-r87j-j422 No score
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling...
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling Protocol (L2TP), executing certain CLI command may cause the system to run out of disk space, excessive disk usage may cause other complications. An administrator can use the following CLI command to monitor the available disk space: user@device> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/gpt/junos 19G 18G 147M 99% /.mount <<<<< running out of space tmpfs 21G 16K 21G 0% /.mount/tmp tmpfs 5.3G 1.7M 5.3G 0% /.mount/mfs This issue affects Juniper Networks Junos OS on MX Series: 17.3R1 and later versions prior to 17.4R3-S5, 18.1 versions prior to 18.1R3-S13, 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2; This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.
- Record
GHSA-9f86-r87j-j422- Weakness
- CWE-400
- Updated
- 2026-11-02
NVD
When a MX Series is configured as a Broadband Network Gateway (BNG) based on Layer 2 Tunneling Protocol (L2TP), executing certain CLI command may cause the system to run out of disk space, excessive disk usage may cause other complications. An administrator can use the following CLI command to monitor the available disk space: user@device> show system storage Filesystem Size Used Avail Capacity Mounted on /dev/gpt/junos 19G 18G 147M 99% /.mount <<<<< running out of space tmpfs 21G 16K 21G 0% /.mount/tmp tmpfs 5.3G 1.7M 5.3G 0% /.mount/mfs This issue affects Juniper Networks Junos OS on MX Series: 17.3R1 and later versions prior to 17.4R3-S5, 18.1 versions prior to 18.1R3-S13, 18.2 versions prior to 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S7; 19.1 versions prior to 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S4, 19.4R3-S2; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R2-S3, 20.2R3; 20.3 versions prior to 20.3R2; 20.4 versions prior to 20.4R1-S1, 20.4R2; This issue does not affect Juniper Networks Junos OS versions prior to 17.3R1.
- Record
CVE-2021-0238- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 2.1 Low
AV:L/AC:L/Au:N/C:N/I:N/A:P - Weakness
- CWE-400
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-0238 is a medium vulnerability (CVSS 5.5) in Juniper Junos, published April 22, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.23%, the 14th percentile. No source names a fixed version.