CVE-2026-48550
Received Received - Intake

Reflected XSS in Nagios Core and Nagios XI via cmd.cgi

Publication date: 2026-08-12

Last updated on: 2026-08-12

Assigner: VulnCheck

Description
Nagios Core before 4.5.14 and Nagios XI before 2026R1.7 are vulnerable to reflected cross-site scripting in cmd.cgi via the NagFormId parameter. An unauthenticated remote attacker can craft a malicious link that, when followed by an authenticated user, executes arbitrary JavaScript in the victim's browser.

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Meta Information

Published
2026-08-12
Last Modified
2026-08-12
Generated
2026-09-01
AI Q&A
2026-08-12
EPSS Evaluated
2026-08-31
NVD
CVE-2026-48550
EUVD
EUVD-2026-57324

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
nagios nagios_core to 4.5.14 (exc)
nagios nagios_xi to 2026R1.7 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Attack-Flow Graph

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Executive Summary

CVE-2026-48550 is a reflected cross-site scripting (XSS) vulnerability in Nagios Core before 4.5.14 and Nagios XI before 2026R1.7. It exists in the cmd.cgi component due to improper input handling in the NagFormId parameter. An attacker can craft a malicious link that executes arbitrary JavaScript when clicked by an authenticated user.

Detection Guidance

To detect this vulnerability, inspect web server logs for cmd.cgi access with unusual NagFormId parameters. Check for requests containing script tags or encoded JavaScript in the NagFormId field. Use tools like curl to test if the parameter reflects unsanitized input.

Impact Analysis

This vulnerability allows an unauthenticated remote attacker to execute arbitrary JavaScript in the browser of an authenticated user. This could lead to session hijacking, theft of sensitive data, or unauthorized actions performed on behalf of the victim.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling unauthorized script execution in user sessions. Reflected XSS may lead to data theft, session hijacking, or unauthorized actions, which could violate confidentiality requirements under these regulations.

Mitigation Strategies

Upgrade Nagios Core to version 4.5.14 or later and Nagios XI to 2026R1.7 or later. If immediate upgrade is not possible, apply input sanitization filters to the NagFormId parameter in cmd.cgi. Restrict access to cmd.cgi via network policies until patched.

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