dbcve.org
GroupsessionApplication

CVE-2021-20876

MEDIUM · 6.8 CVSS v3.1 Published 2021-12-24
Fix available
A fix is available. Upgrade to after 5.1.1 or later.
See remediation →
74/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Path traversal vulnerability in GroupSession Free edition ver5.1.1 and earlier, GroupSession byCloud ver5.1.1 and earlier, and GroupSession ZION ver5.1.1 and earlier allows an attacker with an administrative privilege to obtain sensitive information stored in the hierarchy above the directory on the published site's server via unspecified vectors.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A path traversal vulnerability exists in GroupSession versions 5.1.1 and earlier across Free, byCloud, and ZION editions. An authenticated attacker with administrative privileges can manipulate file path parameters to access sensitive files outside the intended web directory hierarchy, potentially exposing configuration files, credentials, or system files.

MitigationUpgrade to a version beyond 5.1.1 if available, or implement strict input validation and sanitization on all file path parameters to prevent directory traversal sequences (../). Also enforce least-privilege file system permissions on the web server.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
GroupsessionApplication
Affected:<= 5.1.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed GroupSession version
    Access the GroupSession administration panel or check the application metadata/manifest file (typically found in the webapp root or version info endpoint). Compare the version number to the affected range (<= 5.1.1).
    Affected if The installed version is 5.1.1 or any earlier version.
  2. Confirm GroupSession edition
    Verify whether the deployment uses Free, byCloud, or ZION edition. Check the product branding in the login page or administration header.
    Affected if Any of the three editions (Free, byCloud, ZION) are running an affected version.
  3. Identify administrative accounts
    Review the user management section in GroupSession admin panel to list accounts with administrator privileges. Check for users granted the 'administrator' role.
    Affected if There exists any user account with administrative privileges, as this role is required for exploitation.
  4. Assess exposure of file upload/download features
    In the admin panel, locate modules related to file management, attachments, or document handling. Note if these features accept file path parameters or allow directory specification.
    Affected if The application exposes any file path parameter functionality accessible to administrative users.
  5. Review web server access logs
    Examine HTTP access logs for the GroupSession application for suspicious requests containing '../' sequences or unusual file access patterns targeting system directories (e.g., /etc/, /windows/, C:\).
    Affected if Log analysis reveals directory traversal attempts or unauthorized file access from authenticated admin sessions.

You are affected if your GroupSession installation is version 5.1.1 or earlier AND your environment contains at least one user with administrative privileges who can access file path parameter functionality.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 5.1.1
Interim mitigation

Upgrade to a version beyond 5.1.1 if available, or implement strict input validation and sanitization on all file path parameters to prevent directory traversal sequences (../). Also enforce least-privilege file system permissions on the web server.

Recommended fix Moderate confidence

5.1.2 or later

  1. 1. Identify the current GroupSession version in use (Free, byCloud, or ZION edition)
  2. 2. Download the latest version of GroupSession from the official website (groupsession.jp)
  3. 3. Back up the current GroupSession database and configuration files
  4. 4. Deploy the updated GroupSession version (5.1.2 or later) following the standard upgrade procedure
  5. 5. Verify that the administrative interface is accessible and the path traversal vulnerability is no longer present
Caveat Review release notes for any configuration changes or database schema updates that may require adjustments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Groupsession Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-20876 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-20876 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data