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CVE-2023-53689· NVD / CVE Program· CNA VulnCheck

Nagios Fusion < 4.2.0 License Information Reflected XSS

Nagios Fusion versions prior to 4.2.0 contain a reflected cross-site scripting (XSS) vulnerability in the license key configuration flow that can result in execution of attacker-controlled script in the browser of a user who follows a crafted URL. While the application server itself is not directly corrupted by the reflected XSS, the resulting browser compromise can lead to credential/session theft and unauthorized administrative actions.

MediumCVSS 6.0 · v4.0—No exploit Fix available

Noroxi analysis

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Published
Oct 30, 2025
Updated
Jun 17, 2026
EPSS
0.8% · 56th percentile
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Report tools

JSON

Action score

24

Monitor

Low priority for now.

CVSS
24 / 40 · 6.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
6.0
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
nagiosfusion

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • nagios fusionbefore 4.2.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.

  • Nagios Fusion

    • before 4.2.0affected · semver

Same product

nagios: all records

Other highest-scoring records for the same primary product.

  • CVE-2020-28905Improper Input Validation in Nagios Fusion 4.1.8 and earlier allows an authenticated attacker to execute remote code via table pagination.
    43Plan
  • CVE-2020-28901Command Injection in Nagios Fusion 4.1.8 and earlier allows for Privilege Escalation or Code Execution as root via vectors related to corrup
    42Plan
  • CVE-2020-28908Command Injection in Nagios Fusion 4.1.8 and earlier allows for Privilege Escalation to nagios.
    41Plan
  • CVE-2020-28902Command Injection in Nagios Fusion 4.1.8 and earlier allows Privilege Escalation from apache to root in cmd_subsys.php.
    41Plan
  • CVE-2020-28907Incorrect SSL certificate validation in Nagios Fusion 4.1.8 and earlier allows for Escalation of Privileges or Code Execution as root via ve
    40Plan
  • CVE-2020-28904Execution with Unnecessary Privileges in Nagios Fusion 4.1.8 and earlier allows for Privilege Escalation as nagios via installation of a mal
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Nagios Fusion4.2.0Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2023-536900 days apartNagios Fusion < 4.2.0 LDAP/AD Integration Stored XSS
    24Monitor
  • CVE-2023-73120 days apartNagios Fusion < 4.2.0 Email Settings Stored XSS via SMTP/sendmail
    24Monitor
  • CVE-2017-202090 days apartNagios Fusion < 4.0.1 XSS via Users/Servers Page
    20Monitor
  • CVE-2018-251190 days apartNagios Fusion < 4.1.5 XSS via fusionwindow Parameter
    20Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • Administrator privileges are required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
A
Scope
X

Weakness class (CWE)

CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

User content is inserted into the page as HTML. The browser interprets the content as code rather than data.

The bug in code

The whole CWE-79 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
commentEl.innerHTML = comment.body;

Fixed

ts
commentEl.textContent = comment.body;

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records