What is CVE-2025-61987?

CVE-2025-61987 is a medium-severity vulnerability in Groupsession, classified under CWE-1385. CVSS score: 5.3/10. Published 2025-12-12.

How severe is CVE-2025-61987?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Groupsession

CVE-2025-61987

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.

Published 2025-12-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (3.6th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 3.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000

Affected products

Groupsession
Japan Total System Co.,ltd. Groupsession Bycloud — versions prior to ver5.3.3
Japan Total System Co.,ltd. Groupsession Free Edition — versions prior to ver5.3.0
Japan Total System Co.,ltd. Groupsession Zion — versions prior to ver5.3.2

Weakness classification (CWE)

CWE-1385

References

groupsession.jp/info/info-news/security20251208 (Vendor Advisory)
jvn.jp/en/jp/JVN19940619/ (Third Party Advisory)

Frequently asked questions

What is CVE-2025-61987?: CVE-2025-61987 is a medium-severity vulnerability in Groupsession, classified under CWE-1385. CVSS score: 5.3/10. Published 2025-12-12.
How severe is CVE-2025-61987?: Medium severity. CVSS v3 base score is 5.3 out of 10.