CVE-2026-21904
CWE-79Published: April 9, 2026· Updated: Apr 13, 2026
Official Description
An Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Juniper Networks Junos Space allows an attacker to inject script tags in the
list filter field that, when visited by another user, enables the attacker to execute commands with the target's permissions, including an administrator.
This issue affects all versions of Junos Space before 24.1R5 Patch V3.
Technical Analysis
CVE-2026-21904 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.
The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.
From a weakness classification perspective (CWE-79): Cross-site scripting (XSS) vulnerabilities allow attackers to inject malicious scripts into web pages viewed by other users.
CVSS v3.1 Vector Breakdown
Affected Vendors & Products
Exploit & PoC Resources
All References (1)
Quick Facts
Related CVEs (CWE-79)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-21904 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts