VulnerabilityPublished 17 Nov 2025

CVE-2025-40834: Siemens Mendix RichText · Cross-site Scripting

Affects Siemens Mendix RichTextSource CVE Database V5

Not known to be exploited · CVSS 5.7 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

5.7Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Nov 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 26 Oct 2026.

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 or the CVSS exploit maturity 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

Affected software

Product	Affected	Fixed in
npmmendix/richtext`pkg:npm/mendix/richtext`Other threats	Affected =4.0.0	Fixed in–

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AI-suggested

European organizations should implement the following specific mitigations: 1) Upgrade Mendix RichText widgets to version 4.6.1 or later as soon as vendor patches become available. 2) Apply strict input validation and output encoding on all user-supplied content, especially in rich text fields, to prevent injection of malicious scripts. 3) Enforce Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 4) Limit user privileges to the minimum necessary to reduce the impact of potential exploitation. 5) Conduct regular security assessments and penetration testing focused on web application components using Mendix. 6) Monitor web application logs for unusual activity indicative of XSS attempts. 7) Educate users about the risks of interacting with suspicious links or content within corporate applications. 8) Coordinate with Siemens support channels for timely updates and advisories. These steps go beyond generic advice by focusing on the specific widget and environment context.

Description

A vulnerability has been identified in Mendix RichText (All versions >= V4.0.0 < V4.6.1). Affected widget does not properly neutralize the input. This could allow an attacker to execute cross-site scripting attacks.

Impact

For European organizations, this vulnerability poses a significant confidentiality risk, especially for those using Mendix-based applications that incorporate the RichText widget. Attackers exploiting this XSS flaw could hijack user sessions, steal authentication tokens, or perform phishing attacks by injecting malicious scripts. This could lead to unauthorized access to sensitive corporate data or customer information, undermining trust and potentially violating GDPR requirements regarding data protection. Since the vulnerability requires user interaction and some privilege level, the risk is somewhat mitigated but remains relevant in environments with many users or exposed web portals. The impact is heightened in sectors with high regulatory scrutiny such as finance, healthcare, and government services. Additionally, the presence of Siemens as the vendor indicates that critical industrial or infrastructure-related applications might be affected, increasing the potential for targeted attacks. The lack of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits following public disclosure.

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

cert-portal.siemens.com/productcert/html/ssa-190588.html (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Nov 2025, 12:15 UTC

WeaknessesCWE-79

Technical details

References

Community reviews

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