A Cross-site Scripting (XSS) vulnerability in J-Web on Juniper Networks Junos OS allows an attacker to target another user's session thereby gaining access to the users session. The other user session must be active for the attack to succeed. Once successful, the attacker has the same privileges as the user. If the user has root privileges, the attacker may be able to gain full control of the device.

This issue affects:

Juniper Networks Junos OS:

• 12.3 versions prior to 12.3R12-S15 on EX Series;
• 12.3X48 versions prior to 12.3X48-D95 on SRX Series;
• 15.1 versions prior to 15.1R7-S6 on EX Series;
• 15.1X49 versions prior to 15.1X49-D200 on SRX Series;
• 16.1 versions prior to 16.1R7-S7;
• 16.2 versions prior to 16.2R2-S11, 16.2R3;
• 17.1 versions prior to 17.1R2-S11, 17.1R3-S2;
• 17.2 versions prior to 17.2R3-S3;
• 17.3 versions prior to 17.3R2-S5, 17.3R3-S7;
• 17.4 versions prior to 17.4R2-S9, 17.4R3;
• 18.1 versions prior to 18.1R3-S9;
• 18.2 versions prior to 18.2R2-S7, 18.2R3-S3;
• 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3-S1;
• 18.4 versions prior to 18.4R1-S6, 18.4R2-S4, 18.4R3;
• 19.1 versions prior to 19.1R2-S1, 19.1R3;
• 19.2 versions prior to 19.2R1-S3, 19.2R2;
• 19.3 versions prior to 19.3R2.

The following minimal configuration is necessary:

or

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

This issue was found during internal product security testing or research.

This issue has been assigned  CVE-2021-0275 .

The following software releases have been updated to resolve this specific issue: Junos OS 12.3R12-S15, 12.3X48-D95, 15.1R7-S6, 15.1X49-D200, 16.1R7-S7, 16.2R2-S11, 16.2R3, 17.1R2-S11, 17.1R3-S2, 17.2R3-S3, 17.3R2-S5, 17.3R3-S7, 17.4R2-S9, 17.4R3, 18.1R3-S9, 18.2R2-S7, 18.2R3-S3, 18.3R1-S7, 18.3R2-S3, 18.3R3-S1, 18.4R1-S6, 18.4R2-S4, 18.4R3, 19.1R2-S1, 19.1R3, 19.2R1-S3, 19.2R2, 19.3R2, 19.4R1, and all subsequent releases.

This issue is being tracked as  1460150 .

Software releases or updates are available for download at https://support.juniper.net/support/downloads/

There are no viable workarounds for this issue other than disabling J-Web.

To reduce the risk of exploitation of this issue, use access lists or firewall filters to limit access to J-Web to only trusted administrative networks, hosts and users.

2021-04-14: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2021-0275 at cve.mitre.org