CVE-2025-61987Network attack vector

Chat data exposure via unchecked WebSocket origins

Published Dec 12, 2025 · Updated Dec 12, 2025

Missing WebSocket origin validation in affected GroupSession editions allows remote attackers to read chat data through crafted pages. The chat WebSocket handshake accepts connections without validating the browser-supplied Origin header, allowing a page from another origin to receive messages sent to the user. Exposure requires a GroupSession user to access an attacker-controlled page, and the documented consequence is limited to disclosure of chat information.

CVSS severity6.9
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing WebSocket origin validation in affected GroupSession editions allows remote attackers to read chat data through crafted pages. The chat WebSocket handshake accepts connections without validating the browser-supplied Origin header, allowing a page from another origin to receive messages sent to the user. Exposure requires a GroupSession user to access an attacker-controlled page, and the documented consequence is limited to disclosure of chat information.

The record

CVE
CVE-2025-61987
Published
Dec 12, 2025
Updated
Dec 12, 2025
Vendor
Japan Total System Co.,Ltd.
Product
GroupSession ZION
Classifications
CWE-1385
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Dec 12, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=prior to ver5.3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Japan Total System Co.,Ltd. · GroupSession ZIONversion=prior to ver5.3.2
Japan Total System Co.,Ltd. · GroupSession byCloudversion=prior to ver5.3.3
Japan Total System Co.,Ltd. · GroupSession Free editionversion=prior to ver5.3.0

Published CVSS scores

6.9JPCERT/CCCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
5.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1385Missing Origin Validation in WebSockets

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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