Stored cross-site scripting vulnerabilities exist in GroupSession Free edition prior to ver5.3.0, GroupSession byCloud prior to ver5.3.3, a…

published 2025-12-12 10 mo ago modified 2026-10-07 32 d ago also EUVD-2025-203026

cvss: 5.4; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits: 0; none known

Stored cross-site scripting vulnerabilities exist in GroupSession Free edition prior to ver5.3.0, GroupSession byCloud prior to ver5.3.3, and GroupSession ZION prior to ver5.3.2. A logged-in user can prepare a malicious page or URL, and an arbitrary script may be executed on the web browser when another user accesses it.

Patch / fix

fixed in 1

groupsession groupsession er5.3.0, er5.3.2, er5.3.3

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 10 mo ago (2025-12-12)

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	5.4	CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
CNA	4.0	4.8	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA	4.0	4.8	CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

Japan Total System Co.,Ltd. GroupSession Free edition
Japan Total System Co.,Ltd. GroupSession byCloud
Japan Total System Co.,Ltd. GroupSession ZION

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

groupsession.jp /info/info-news/security20251208
vendor-advisory
jvn.jp /en/jp/JVN19940619/
third-party-advisory

Sources

CVE List CVE-2025-53523
NVD CVE-2025-53523

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary