vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2021-20789

MEDIUM
6.1
CVSS Score
Published: July 28, 2021 at 12:45 AM UTC
Updated: June 17, 2026 at 03:34 AM UTC
4 products affected across 2 vendorsGroupsessionGroupsession ZionGroupsession Bycloud

Using GroupSession by Japan Total System Co.,Ltd.?

Get instant alerts when new vulnerabilities affect GroupSession - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
MEDIUM6.1
Exploit prediction
EPSS 0.9%

Description

Open redirect vulnerability in GroupSession (GroupSession Free edition from ver2.2.0 to the version prior to ver5.1.0, GroupSession byCloud from ver3.0.3 to the version prior to ver5.1.0, and GroupSession ZION from ver3.0.3 to the version prior to ver5.1.0) allows a remote attacker to redirect a user to an arbitrary web site and conduct a phishing attack via a specially crafted URL.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Groupsession· Groupsession
95%
2.20 ≤ v < 5.1.0
Affected range stops below 5.1.0, so it looks safe — our inference, not a vendor statement
Groupsession Bycloud· Groupsession
95%
3.0.3 ≤ v < 5.1.0
Affected range stops below 5.1.0, so it looks safe — our inference, not a vendor statement
Groupsession Zion· Groupsession
95%
3.0.3 ≤ v < 5.1.0
Affected range stops below 5.1.0, so it looks safe — our inference, not a vendor statement
GroupSession· Japan Total System
60%
GroupSession Free edition from ver2.2.0 to the version prior to ver5.1.0, GroupSession byCloud from ver3.0.3 to the version prior to ver5.1.0, and GroupSession ZION from ver3.0.3 to the version prior to ver5.1.0

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_MISCVendor Advisory
Source: [email protected]
https://groupsession.jp/info/info-news/security202107
x_refsource_MISCThird Party Advisory
Source: [email protected]
https://jvn.jp/en/jp/JVN86026700/index.html

CVSS

6.1MEDIUM[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-601

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card