CVE-2021-31372Network attack vector

Authenticated root escalation through undisclosed J-Web input

Published Oct 19, 2021 · Updated Sep 16, 2024

Improper input validation in Juniper Networks Junos OS J-Web allows remote authenticated users to escalate privileges to root. Juniper has not published the affected input, handler, or incorrect validation operation within J-Web. Exploitation requires an authenticated J-Web account and an enabled HTTP or HTTPS web-management service, and success grants root control of the device.

CVSS severity8.8
High
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in Juniper Networks Junos OS J-Web allows remote authenticated users to escalate privileges to root. Juniper has not published the affected input, handler, or incorrect validation operation within J-Web. Exploitation requires an authenticated J-Web account and an enabled HTTP or HTTPS web-management service, and success grants root control of the device.

The record

CVE
CVE-2021-31372
Published
Oct 19, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-20, T1068
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 19, 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=18.4 <18.4R3-S9
  2. Affected versionversion=19.1 <19.1R3-S6
  3. Affected versionversion=19.2 <19.2R3-S3
  4. Affected versionversion=19.3 <19.3R3-S3
  5. Affected versionversion=19.4 <19.4R3-S5
  6. Affected versionversion=20.1 <20.1R3-S1
  7. Affected versionversion=20.2 <20.2R3-S2
  8. Affected versionversion=20.3 <20.3R3-S1
  9. Affected versionversion=20.4 <20.4R3
  10. Affected versionversion=21.1 <21.1R2, 21.1R3
  11. Affected versionversion=21.2 <21.2R1-S1, 21.2R2
  12. Affected versionversion=unspecified <18.3R3-S5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=18.4 <18.4R3-S9; version=19.1 <19.1R3-S6; version=19.2 <19.2R3-S3; version=19.3 <19.3R3-S3; version=19.4 <19.4R3-S5; version=20.1 <20.1R3-S1; version=20.2 <20.2R3-S2; version=20.3 <20.3R3-S1; version=20.4 <20.4R3; version=21.1 <21.1R2, 21.1R3; version=21.2 <21.2R1-S1, 21.2R2; version=unspecified <18.3R3-S5

Published CVSS scores

8.8Juniper Networks, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
9.0NIST NVDAV:N/AC:L/Au:S/C:C/I:C/A:C

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
T1068Exploitation for Privilege Escalation

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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