CVE-2025-40899Network attack vector

Stored XSS via unsafe custom-field rendering

Published Apr 15, 2026 · Updated Apr 15, 2026

Stored XSS in Nozomi Networks Guardian and CMC before 26.0.0 allows remote authenticated users to run script in a victim's browser. The Assets and Nodes custom-field handling stores an insufficiently validated field value and renders its JavaScript payload when either page is viewed. Custom-fields privileges and a victim page view are required; the script acts in the victim's session to change data, interrupt service, or read limited sensitive information.

CVSS severity7.1
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in Nozomi Networks Guardian and CMC before 26.0.0 allows remote authenticated users to run script in a victim's browser. The Assets and Nodes custom-field handling stores an insufficiently validated field value and renders its JavaScript payload when either page is viewed. Custom-fields privileges and a victim page view are required; the script acts in the victim's session to change data, interrupt service, or read limited sensitive information.

The record

CVE
CVE-2025-40899
Published
Apr 15, 2026
Updated
Apr 15, 2026
Vendor
Nozomi Networks
Product
Guardian
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <26.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nozomi Networks · Guardianversion=0 <26.0.0
Nozomi Networks · Central Management Console (CMC)version=0 <26.0.0

Published CVSS scores

7.1Nozomi Networks Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:H/VA:H/SC:L/SI:L/SA:L
8.9Nozomi Networks Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:H

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
Privilegesauthenticated
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.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo