What is CVE-2026-21904?

CVE-2026-21904 is a medium-severity vulnerability in Juniper Junos Space, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-09.

How severe is CVE-2026-21904?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Juniper Junos Space

CVE-2026-21904

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.

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (11.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Juniper Junos_space — versions 1.0, 1.1, 1.2
Juniper Networks Junos Space — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

sirt@juniper.net (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-21904?: CVE-2026-21904 is a medium-severity vulnerability in Juniper Junos Space, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-04-09.
How severe is CVE-2026-21904?: Medium severity. CVSS v3 base score is 6.1 out of 10.