CVE-2026-21904Network attack vector

Administrator-context script execution via unneutralized ilpFilter reflection

Published Apr 9, 2026 · Updated Apr 9, 2026

Reflected XSS in Junos Space before 24.1R5 Patch V3 allows remote attackers to execute script with a visiting user's permissions. The nLegacy.jsp page returns the ilpFilter list-filter value as executable markup without neutralizing injected script tags. No authentication is required to craft the input, but another user must visit it; an administrator's session grants administrator-level actions.

CVSS severity5.1
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Junos Space before 24.1R5 Patch V3 allows remote attackers to execute script with a visiting user's permissions. The nLegacy.jsp page returns the ilpFilter list-filter value as executable markup without neutralizing injected script tags. No authentication is required to craft the input, but another user must visit it; an administrator's session grants administrator-level actions.

The record

CVE
CVE-2026-21904
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Juniper Networks
Product
Junos Space
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <24.1R5 Patch V3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Juniper Networks · Junos Spaceversion=0 <24.1R5 Patch V3

Published CVSS scores

6.1Juniper NetworksCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.1Juniper NetworksCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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