CVE-2021-31385Network attack vector

Root privilege escalation via J-Web path traversal

Published Oct 19, 2021 · Updated Sep 16, 2024

Path traversal in J-Web in Juniper Networks Junos OS allows remote authenticated users with low privileges to gain root access. Juniper identifies improper pathname restriction in J-Web but does not disclose the affected request handler, path field, or filesystem operation. The issue is reachable only when HTTP or HTTPS web management is enabled and the attacker holds a low-privileged account.

CVSS severity8.8
High
EPSS probability1.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Path traversal in J-Web in Juniper Networks Junos OS allows remote authenticated users with low privileges to gain root access. Juniper identifies improper pathname restriction in J-Web but does not disclose the affected request handler, path field, or filesystem operation. The issue is reachable only when HTTP or HTTPS web management is enabled and the attacker holds a low-privileged account.

The record

CVE
CVE-2021-31385
Published
Oct 19, 2021
Updated
Sep 16, 2024
Vendor
Juniper Networks
Product
Junos OS
Classifications
CWE-22, 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=12.3 <12.3R12-S19
  2. Affected versionversion=15.1 <15.1R7-S10
  3. Affected versionversion=18.3 <18.3R3-S5
  4. Affected versionversion=18.4 <18.4R3-S9
  5. Affected versionversion=19.1 <19.1R3-S6
  6. Affected versionversion=19.2 <19.2R1-S7, 19.2R3-S3
  7. Affected versionversion=19.3 <19.3R3-S3
  8. Affected versionversion=19.4 <19.4R3-S5
  9. Affected versionversion=20.1 <20.1R2-S2, 20.1R3-S1
  10. Affected versionversion=20.2 <20.2R3-S2
  11. Affected versionversion=20.3 <20.3R3
  12. Affected versionversion=20.4 <20.4R2-S1, 20.4R3
  13. Affected versionversion=21.1 <21.1R1-S1, 21.1R2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Juniper Networks · Junos OSversion=12.3 <12.3R12-S19; version=15.1 <15.1R7-S10; version=18.3 <18.3R3-S5; version=18.4 <18.4R3-S9; version=19.1 <19.1R3-S6; version=19.2 <19.2R1-S7, 19.2R3-S3; version=19.3 <19.3R3-S3; version=19.4 <19.4R3-S5; version=20.1 <20.1R2-S2, 20.1R3-S1; version=20.2 <20.2R3-S2; version=20.3 <20.3R3; version=20.4 <20.4R2-S1, 20.4R3; version=21.1 <21.1R1-S1, 21.1R2

Published CVSS scores

8.8Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.5NISTAV:N/AC:M/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo