CVE-2026-48550

Nagios Core / XI cmd.cgi Reflected XSS via NagFormId Parameter

MEDIUM

6.1

CVSS Score

Published: August 12, 2026 at 04:30 PM UTC

Updated: September 8, 2026 at 08:39 PM UTC

4 products affected across 2 vendorsNagios XINagios CoreNagios XI

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Severity

MEDIUM6.1

Exploit prediction

EPSS 0.4%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nagios Core · Nagios

95%

v < 4.5.14

Affected range stops below 4.5.14, so it looks safe — our inference, not a vendor statement

Nagios XI · Nagios

95%

v < 2026r1.7

Affected range stops below 2026r1.7, so it looks safe — our inference, not a vendor statement

Nagios Core · Nagios Enterprises

60%

v < 4.5.14

Affected range stops below 4.5.14, so it looks safe — our inference, not a vendor statement

Nagios XI · Nagios Enterprises

60%

v < 2026R1.7

Affected range stops below 2026R1.7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://www.nagios.com/security-disclosures/nagios-core/

References (3)

Vendor AdvisoryPatch

Source: cverecord

https://www.nagios.com/security-disclosures/nagios-core/

Release Notes

Source: cverecord

https://github.com/NagiosEnterprises/nagioscore/blob/master/Changelog

Third Party Advisory

Source: cverecord

https://www.vulncheck.com/advisories/nagios-core-xi-cmd-cgi-reflected-xss-via-nagformid-parameter

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

6.1MEDIUMVulnCheck

Attack Vector: NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: REQUIRED
Scope: CHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusAWAITING ANALYSIS

CWE

CWE-79

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