CVE-2023-53690VulnerabilityPublished 30 Oct 2025Updated 17 Nov 2025

CVE-2023-53690: Nagios Fusion · XSS or 'Cross-site Scripting'

Affects Nagios FusionSource CVE Database V5

Not known to be exploited · CVSS 6.2 Medium : upgrade to 4.2.0 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.2Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.2.0

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: High
User Interaction: Passive
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: None
Subsequent system confidentiality: High
Subsequent system integrity: High
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: High: The attacker requires privileges that provide significant (e.g., administrative) control over the vulnerable system allowing full access to the vulnerable system’s settings and files.
User Interaction: Passive: Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker’s payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: High: There is a total loss of confidentiality, resulting in all resources within the Subsequent System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Subsequent system integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Subsequent System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Subsequent System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 30 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Nagios Fusion to 4.2.0.

Affected software

Product	Affected	Fixed in
Nagios Fusion	Affected =0 <4.2.0	Fixed in 4.2.0

AI-suggested

To mitigate CVE-2023-53690, European organizations should: 1) Upgrade Nagios Fusion to version 4.2.0 or later, where the vulnerability has been addressed. 2) Restrict administrative access to the Nagios Fusion interface strictly to trusted personnel and enforce strong authentication mechanisms, such as multi-factor authentication (MFA), to reduce the risk of compromised admin accounts. 3) Implement rigorous input validation and output encoding controls on any custom integrations or scripts interacting with Nagios Fusion to prevent injection of malicious content. 4) Regularly audit and monitor changes to LDAP/AD authentication server configurations to detect unauthorized modifications promptly. 5) Educate administrators about the risks of stored XSS and encourage cautious handling of configuration inputs. 6) Employ Content Security Policy (CSP) headers on the Nagios Fusion web interface to limit the execution of unauthorized scripts. 7) Monitor logs for suspicious activity related to authentication server configuration changes or unusual administrative UI access patterns. 8) Consider network segmentation and access controls to limit exposure of the Nagios Fusion administrative interface to only necessary management networks.

Description

CVE-2023-53690 is a stored cross-site scripting (XSS) vulnerability affecting Nagios Fusion versions prior to 4.2.0. The flaw exists in the LDAP/AD authentication-server configuration, where unsanitized user input can be stored and later rendered in the administrative UI. This allows an attacker with privileges to add authentication servers to inject malicious JavaScript that executes in the browsers of other users viewing the affected page. Exploitation requires high privileges to add LDAP/AD servers and user interaction to trigger the payload. The vulnerability has a CVSS 4.0 score of 6.2, indicating medium severity. No known exploits are currently reported in the wild.

Impact

For European organizations, the impact of CVE-2023-53690 can be substantial, especially for those relying on Nagios Fusion for centralized IT infrastructure monitoring and management. Successful exploitation could allow an attacker with administrative access to inject malicious scripts that execute in other administrators' browsers, potentially leading to session hijacking, theft of credentials, or unauthorized actions within the monitoring platform. This could result in disruption of monitoring capabilities, delayed detection of incidents, or unauthorized changes to monitoring configurations. Given that Nagios Fusion often integrates with critical network and server infrastructure, compromise could cascade into broader operational impacts, including data loss, service outages, or exposure of sensitive network topology and status information. European organizations in sectors such as finance, telecommunications, energy, and government, which rely heavily on robust monitoring solutions, may face increased risks of operational disruption and regulatory non-compliance if this vulnerability is exploited. The requirement for administrative privileges to exploit somewhat limits the attack surface, but insider threats or compromised administrator accounts could be leveraged. Additionally, the vulnerability could be used as a foothold for further lateral movement or privilege escalation within the IT environment.

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #1OWASP Top 10 A05:2025: Injection (opens in a new tab)
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.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Implementation · Architecture and Design
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages.
Architecture and Design · Implementation · Attack Surface Reduction
Understand all the potential areas where untrusted inputs can enter your software: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide…
OWASP Cheat Sheets
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Injection Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
OWASP ASVS 4.0.3
V5.3.3 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
XSS Using MIME Type Mismatch (opens in a new tab)
DOM-Based XSS (opens in a new tab)
Reflected XSS (opens in a new tab)
Stored XSS (opens in a new tab)
Cross-Site Scripting (XSS) (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Nov 2025, 22:17 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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