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             AUSCERT External Security Bulletin Redistribution

  JSA11253 - 2021-10 Security Bulletin: Junos OS: J-Web: A path traversal
         vulnerability allows an authenticated attacker to elevate
                 their privileges to root (CVE-2021-31385)
                              17 January 2022


        AusCERT Security Bulletin Summary

Product:           Junos OS
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Root Compromise -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-31385  

Original Bulletin: 

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2021-10 Security Bulletin: Junos OS: J-Web: A path traversal vulnerability allows
an authenticated attacker to elevate their privileges to root (CVE-2021-31385)

Article ID  : JSA11253
Last Updated: 14 Jan 2022
Version     : 2.0

Product Affected:
This issue affects Junos OS 12.3, 15.1, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4,
20.1, 20.2, 20.3, 20.4, 21.1.

An Improper Limitation of a Pathname to a Restricted Directory ('Path
Traversal') vulnerability in J-Web of Juniper Networks Junos OS allows any
low-privileged authenticated attacker to elevate their privileges to root.

This issue affects:

Juniper Networks Junos OS

  o 12.3 versions prior to 12.3R12-S19;
  o 15.1 versions prior to 15.1R7-S10;
  o 18.3 versions prior to 18.3R3-S5;
  o 18.4 versions prior to 18.4R3-S9;
  o 19.1 versions prior to 19.1R3-S6;
  o 19.2 versions prior to 19.2R1-S7, 19.2R3-S3;
  o 19.3 versions prior to 19.3R3-S3;
  o 19.4 versions prior to 19.4R3-S5;
  o 20.1 versions prior to 20.1R2-S2, 20.1R3-S1;
  o 20.2 versions prior to 20.2R3-S2;
  o 20.3 versions prior to 20.3R3;
  o 20.4 versions prior to 20.4R2-S1, 20.4R3;
  o 21.1 versions prior to 21.1R1-S1, 21.1R2.

The following minimal configuration is necessary:

[system services web-management http]


[system services web-management https]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was discovered during external security research.

This issue has been assigned CVE-2021-31385 .


The following software releases have been updated to resolve this specific
issue: 12.3R12-S19, 15.1R7-S10, 18.3R3-S5, 18.4R3-S9, 19.1R3-S6, 19.2R1-S7,
19.2R3-S3, 19.3R3-S3, 19.4R3-S5, 20.1R2-S2, 20.1R3-S1, 20.2R3-S2, 20.3R3,
20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.2R1, and all subsequent releases.

This issue is being tracked as 1591145 .


There are no viable workarounds for these issues other than disabling J-Web.

To reduce the risk of exploitation of these issues, use access lists or
firewall filters to limit access to only trusted administrative networks, hosts
and users.

Software releases or updates are available for download at https://
Modification History:

2021-10-13: Initial Publication.

CVSS Score:
8.8 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)

Severity Level:

Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common
Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

Andy Coles of Microsoft MSRC Vulnerabilities and Mitigations Team

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