CVE-2021-33179Network attack vector

Session data exposure via reflected URL script

Published Oct 14, 2021 · Updated Aug 3, 2024

Reflected XSS in Nagios XI before 5.8.4 allows remote attackers to execute JavaScript in an authenticated user's browser via a crafted URL. The Core Config Manager interface reflects attacker-controlled URL content into a response without sufficient output encoding. Exploitation requires an authenticated victim to open the link; the script can access Nagios XI session data and alter browser-visible content.

CVSS severity6.1
Medium
EPSS probability11.68%
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 Nagios XI before 5.8.4 allows remote attackers to execute JavaScript in an authenticated user's browser via a crafted URL. The Core Config Manager interface reflects attacker-controlled URL content into a response without sufficient output encoding. Exploitation requires an authenticated victim to open the link; the script can access Nagios XI session data and alter browser-visible content.

The record

CVE
CVE-2021-33179
Published
Oct 14, 2021
Updated
Aug 3, 2024
Vendor
Nagios Enterprises, LLC
Product
Nagios XI
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=<5.8.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nagios Enterprises, LLC · Nagios XIversion=<5.8.4

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A: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')
T1204.001User Execution: Malicious Link

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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