CVE-2021-47689Network attack vectorHinoki check available

Browser script execution via unescaped template actions

Published Oct 30, 2025 · Updated Oct 30, 2025

Cross-site scripting in Nagios XI before 5.8.0 allows remote authenticated users to execute JavaScript in another user's browser. The Core Config Manager Templates pages render user-controlled values in the Active/Actions button UI without sufficient validation or output escaping. A low-privileged account must plant the input and a victim must open the affected page, exposing or altering data available to that browser session without interrupting the service.

CVSS severity5.1
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Cross-site scripting in Nagios XI before 5.8.0 allows remote authenticated users to execute JavaScript in another user's browser. The Core Config Manager Templates pages render user-controlled values in the Active/Actions button UI without sufficient validation or output escaping. A low-privileged account must plant the input and a victim must open the affected page, exposing or altering data available to that browser session without interrupting the service.

The record

CVE
CVE-2021-47689
Published
Oct 30, 2025
Updated
Oct 30, 2025
Vendor
Nagios Enterprises, LLC
Product
Nagios XI
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 30, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 2025Record 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 <5.8.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nagios Enterprises, LLC · Nagios XIversion=0 <5.8.0

Published CVSS scores

5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
5.1VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript/JScript

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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