VulnerabilityPublished 16 Oct 2025

CVE-2025-53858: NEOJAPAN ChatLuck · Cross-site Scripting (XSS)

Affects NEOJAPAN ChatLuckSource CVE Database V5

Not known to be exploited · CVSS 5.4 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.0 base score

5.4Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 16 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 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
NEOJAPAN Inc. ChatLuck	Affected <=6.6	Fixed in–

AI-suggested

European organizations should immediately audit their ChatLuck deployments to identify affected versions (V6.6 R2.0 and earlier). Until an official patch is released, administrators should implement strict input validation and sanitization at the application or web server level, potentially using web application firewalls (WAFs) configured to detect and block XSS payloads targeting chat room inputs. User awareness training should emphasize caution when interacting with unexpected or suspicious chat messages. Restricting chat room access to trusted users and limiting privileges can reduce exploitation risk. Monitoring logs for unusual script injection attempts or anomalous user behavior is critical. Organizations should also consider isolating ChatLuck instances from critical network segments to contain potential breaches. Once a vendor patch becomes available, prompt application of updates is essential. Additionally, implementing Content Security Policy (CSP) headers can help mitigate the impact of injected scripts by restricting script execution sources.

Description

ChatLuck contains a cross-site scripting vulnerability in Chat Rooms. If exploited, an arbitrary script may be executed on the web browser of the user who is accessing the product.

Impact

For European organizations, the exploitation of this XSS vulnerability in ChatLuck could lead to unauthorized access to sensitive communications, session hijacking, and potential lateral movement within corporate networks. Since ChatLuck is a collaboration tool, attackers could leverage this vulnerability to impersonate users, steal confidential information, or distribute malware through malicious scripts. The medium severity suggests a moderate risk, but the impact on confidentiality and integrity could be significant in sectors handling sensitive data such as finance, healthcare, and government. The requirement for user interaction and some privilege level reduces the likelihood of widespread automated exploitation but does not eliminate targeted attacks. Organizations relying heavily on ChatLuck for internal communications may face reputational damage and compliance risks if sensitive data is compromised. Additionally, the vulnerability could be exploited to bypass access controls or escalate privileges within the application context, further increasing risk.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 16 Oct 2025, 09:15 UTC

Technical details

References

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