CVE-2021-31357

Authenticated shell access via tcpdump command injection

Published Oct 19, 2021 · Updated Sep 17, 2024

Command injection in affected Junos OS Evolved releases allows remote authenticated users to execute shell commands through the CLI. The tcpdump command processor fails to neutralize command elements before invoking the shell, bypassing configured command authorization restrictions. Authenticated CLI access is required, and execution remains limited to the assigned privilege level, but restricted super-users gain unrestricted administrative shell access.

CVSS severity7.8
High
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in affected Junos OS Evolved releases allows remote authenticated users to execute shell commands through the CLI. The tcpdump command processor fails to neutralize command elements before invoking the shell, bypassing configured command authorization restrictions. Authenticated CLI access is required, and execution remains limited to the assigned privilege level, but restricted super-users gain unrestricted administrative shell access.

The record

CVE
CVE-2021-31357
Published
Oct 19, 2021
Updated
Sep 17, 2024
Vendor
Juniper Networks
Product
Junos OS Evolved
Classifications
CWE-78, CWE-77, T1059.008
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 19, 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

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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=20.4 <20.4R2-S2-EVO
  2. Affected versionversion=21.1 <21.1R2-EVO
  3. Affected versionversion=21.2 <21.2R1-S1-EVO, 21.2R2-EVO
  4. Affected versionversion=unspecified <20.3R2-S1-EVO

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OS Evolvedversion=20.4 <20.4R2-S2-EVO; version=21.1 <21.1R2-EVO; version=21.2 <21.2R1-S1-EVO, 21.2R2-EVO; version=unspecified <20.3R2-S1-EVO

Published CVSS scores

7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C
7.8Juniper NetworksCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-77Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1059.008Network Device CLI

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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