VulnerabilityPublished 12 Dec 2025

CVE-2025-54407: Japan Total System GroupSession Free edition · Cross-site Scripting (XSS)

Affects Japan Total System GroupSession Free editionSource CVE Database V5

Not known to be exploited · CVSS 6.1 Medium : upgrade to 5.3.0 when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.0 base score

6.1Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.3.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
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: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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 12 Dec 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

Upgrade Japan Total System GroupSession Free edition to 5.3.0.

Affected software

Product	Affected	Fixed in
Japan Total System Co.,Ltd. GroupSession Free edition	Affected <5.3.0	Fixed in 5.3.0

AI-suggested

European organizations should immediately identify any deployments of GroupSession Free edition prior to 5.3.0, byCloud prior to 5.3.3, or ZION prior to 5.3.2. The primary mitigation is to upgrade these products to the fixed versions where the vulnerability is patched. In parallel, organizations should implement strict input validation and output encoding on all user-supplied data within GroupSession to prevent script injection. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. Educate users about the risks of clicking on suspicious links or URLs, especially those received via email or messaging platforms. Conduct regular security assessments and penetration testing focused on web application vulnerabilities. Network-level protections such as web application firewalls (WAFs) can be tuned to detect and block typical XSS payloads targeting GroupSession endpoints. Finally, monitor logs for unusual user activity that could indicate exploitation attempts.

Description

Stored cross-site scripting vulnerability exists in GroupSession Free edition prior to ver5.3.0, GroupSession byCloud prior to ver5.3.3, and GroupSession ZION prior to ver5.3.2. If a user accesses a crafted page or URL, an arbitrary script may be executed on the web browser of the user.

Impact

For European organizations, this vulnerability poses a risk primarily to confidentiality and integrity of user data within GroupSession environments. Attackers exploiting this XSS flaw could steal session tokens, enabling unauthorized access to sensitive collaboration data or impersonation of legitimate users. This could lead to data leakage, unauthorized data modification, or further pivoting within the network. Since GroupSession is used for group communication and document sharing, exploitation could disrupt business workflows and compromise sensitive corporate information. The requirement for user interaction means phishing or social engineering could be used to lure users into triggering the exploit. Although availability is not directly impacted, the indirect consequences of data breaches or unauthorized access could be significant. The absence of known exploits in the wild currently reduces immediate risk, but the medium CVSS score and the nature of the software suggest that targeted attacks against European organizations using affected versions are plausible.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 Dec 2025, 08:32 UTC

Technical details

References

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