Vulnerability Monitor

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CVE-2021-31356


A command injection vulnerability in command processing on Juniper Networks Junos OS Evolved allows an attacker with authenticated CLI access to be able to bypass configured access protections to execute arbitrary shell commands within the context of the current user. The vulnerability allows an attacker to bypass command authorization restrictions assigned to their specific user account and execute commands that are available to the privilege level for which the user is assigned. For example, a user that is in the super-user login class, but restricted to executing specific CLI commands could exploit the vulnerability to execute any other command available to an unrestricted admin user. This vulnerability does not increase the privilege level of the user, but rather bypasses any CLI command restrictions by allowing full access to the shell. This issue affects Juniper Networks Junos OS Evolved: All versions prior to 20.4R3-S1-EVO; All versions of 21.1-EVO and 21.2-EVO.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.8, requiring local system access to exploit with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 1 product from juniper organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2021-10-19T19:15:08.897

Last Modified

2024-11-21T06:05:29.490

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 7.8 (HIGH)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:C/I:C/A:C

  • Access Vector: LOCAL
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: COMPLETE
  • Integrity Impact: COMPLETE
  • Availability Impact: COMPLETE
Exploitability Score

3.9

Impact Score

10.0

Weaknesses
  • Type: Secondary
    CWE-77
  • Type: Primary
    CWE-78

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System juniper junos_os_evolved ≤ 20.3 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 20.4 Yes
Operating System juniper junos_os_evolved 21.1 Yes
Operating System juniper junos_os_evolved 21.1 Yes
Operating System juniper junos_os_evolved 21.1 Yes
Operating System juniper junos_os_evolved 21.1 Yes
Operating System juniper junos_os_evolved 21.2 Yes
Operating System juniper junos_os_evolved 21.2 Yes
Operating System juniper junos_os_evolved 21.2 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For juniper's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.