CVE-2021-47694Network attack vectorHinoki check available

Script execution via double-encoded Test Command input

Published Oct 30, 2025 · Updated Oct 30, 2025

Reflected XSS in Nagios XI before 5.8.6 allows remote authenticated users to execute script in a victim's browser via Test Command input. The Core Config Manager Test Command page reflects double-encoded HTML entities without sufficient output escaping, turning supplied markup into executable script. Low-privilege access and passive victim interaction are required, and successful exploitation exposes data and actions available to the victim's Nagios XI session.

CVSS severity5.1
Medium
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Reflected XSS in Nagios XI before 5.8.6 allows remote authenticated users to execute script in a victim's browser via Test Command input. The Core Config Manager Test Command page reflects double-encoded HTML entities without sufficient output escaping, turning supplied markup into executable script. Low-privilege access and passive victim interaction are required, and successful exploitation exposes data and actions available to the victim's Nagios XI session.

The record

CVE
CVE-2021-47694
Published
Oct 30, 2025
Updated
Oct 30, 2025
Vendor
Nagios Enterprises, LLC
Product
Nagios XI
Classifications
CWE-116, CWE-79, CAPEC-591, T1203
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 <5.8.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nagios Enterprises, LLC · Nagios XIversion=0 <5.8.6

Published CVSS scores

6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/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.

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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-116Improper Encoding or Escaping of Output
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-591Reflected XSS
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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