VulnerabilityPublished 12 Dec 2025

CVE-2025-61987: Japan Total System GroupSession Free edition · Missing Origin Validation in WebSockets

Affects Japan Total System GroupSession Free editionSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 5.3.0 when convenient.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.0 base score

5.3Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% 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:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
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: 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: None: The vulnerable system can be exploited without any interaction from any user.
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: 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: 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 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 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 prioritize upgrading all affected GroupSession products to versions 5.3.0 or later (Free edition), 5.3.3 or later (byCloud), and 5.3.2 or later (ZION) to ensure the vulnerability is patched. In addition to patching, administrators should implement strict WebSocket origin validation policies to reject connections from untrusted or unknown origins. Network-level controls such as Web Application Firewalls (WAFs) can be configured to monitor and block suspicious WebSocket traffic. User education campaigns should warn about the risks of visiting untrusted websites while connected to internal collaboration tools. Organizations should also audit their GroupSession deployments to identify any exposed WebSocket endpoints accessible from untrusted networks and consider network segmentation to limit exposure. Monitoring and logging WebSocket connection attempts can help detect potential exploitation attempts. Finally, ensure compliance with data protection regulations by reviewing data handling and breach response procedures related to chat data.

Description

GroupSession Free edition prior to ver5.3.0, GroupSession byCloud prior to ver5.3.3, and GroupSession ZION prior to ver5.3.2.do not validate origins in WebSockets. If a user accesses a crafted page, Chat information sent to the user may be exposed.

Impact

For European organizations, this vulnerability poses a risk of unauthorized disclosure of sensitive chat communications within GroupSession environments. Organizations relying on GroupSession for internal collaboration or client communications may suffer confidentiality breaches if users access malicious web content while connected to the vulnerable system. This could lead to exposure of proprietary information, personal data, or strategic discussions, potentially violating GDPR and other data protection regulations. Although the vulnerability does not affect data integrity or availability, the confidentiality impact alone can damage organizational trust and compliance posture. The ease of exploitation (no authentication or user interaction beyond visiting a page) increases the risk, especially in environments where users may access untrusted web content. The absence of known exploits currently reduces immediate risk but does not eliminate the potential for future attacks. Organizations with remote or hybrid workforces using GroupSession are particularly vulnerable due to increased exposure to web-based threats.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 Dec 2025, 08:30 UTC

Technical details

References

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