CVE-2026-39355 Overview
CVE-2026-39355 is a critical broken access control vulnerability affecting Genealogy, a family tree PHP application. Prior to version 5.9.1, the application contains a flaw that allows any authenticated user to transfer ownership of arbitrary non-personal teams to themselves. This enables complete takeover of other users' team workspaces and unrestricted access to all genealogy data associated with the compromised team.
Critical Impact
Any authenticated user can hijack team ownership and gain full access to sensitive genealogy data belonging to other users, representing a complete compromise of data confidentiality and integrity.
Affected Products
- Genealogy PHP Application versions prior to 5.9.1
Discovery Timeline
- 2026-04-07 - CVE-2026-39355 published to NVD
- 2026-04-08 - Last updated in NVD database
Technical Details for CVE-2026-39355
Vulnerability Analysis
This vulnerability is classified under CWE-862 (Missing Authorization), indicating that the application fails to properly verify whether a user is authorized to perform the team ownership transfer action. The flaw resides in the access control logic governing team management functionality within the Genealogy application.
When an authenticated user initiates a request to transfer team ownership, the application does not adequately validate whether the requesting user has legitimate authority over the target team. This missing authorization check allows any authenticated user to manipulate the ownership transfer mechanism for teams they do not own or manage, provided those teams are non-personal (shared/collaborative teams).
The impact is severe as it enables complete takeover of team workspaces. Once ownership is transferred, the attacker gains unrestricted access to all genealogy data, family trees, and personal information associated with the compromised team. This can include sensitive information such as birth dates, death records, family relationships, and other private genealogical data.
Root Cause
The root cause is a missing authorization check (CWE-862) in the team ownership transfer functionality. The application verifies that a user is authenticated but fails to verify that the authenticated user has the necessary permissions to perform ownership transfer operations on the specified team. This represents a fundamental broken access control design flaw where authentication is confused with authorization.
Attack Vector
The attack is network-accessible and requires only low-privilege authenticated access to the application. An attacker simply needs a valid account on the Genealogy application to exploit this vulnerability. No user interaction is required from the victim, and the scope is changed as the attacker can affect resources belonging to other users.
The attacker would identify target non-personal teams within the application and craft requests to the team ownership transfer endpoint. Due to the missing authorization checks, the application processes these requests as legitimate, transferring ownership to the attacker. This provides immediate and complete access to all team resources and genealogy data.
Detection Methods for CVE-2026-39355
Indicators of Compromise
- Unexpected changes in team ownership records within the Genealogy application database
- Audit logs showing ownership transfer requests from users who are not team owners or administrators
- Users reporting loss of access to their team workspaces without initiating any changes
Detection Strategies
- Monitor application audit logs for team ownership transfer events, especially those initiated by users who were not previous team owners
- Implement alerting on bulk or rapid ownership transfer operations that may indicate automated exploitation
- Review database records for anomalous changes to team ownership fields
Monitoring Recommendations
- Enable detailed logging for all team management operations including ownership transfers
- Establish baseline patterns for legitimate team ownership changes and alert on deviations
- Consider implementing real-time monitoring of access control events within the Genealogy application
How to Mitigate CVE-2026-39355
Immediate Actions Required
- Upgrade the Genealogy application to version 5.9.1 or later immediately
- Audit existing team ownership records to identify any unauthorized transfers that may have already occurred
- Review application access logs for suspicious team management activity
- Consider temporarily restricting team ownership transfer functionality until patching is complete
Patch Information
This vulnerability is fixed in Genealogy version 5.9.1. Organizations should upgrade to this version or later to remediate the vulnerability. For additional details, refer to the GitHub Security Advisory.
Workarounds
- If immediate patching is not possible, consider implementing additional access control at the web server or application firewall level to restrict access to team management endpoints
- Temporarily disable the team ownership transfer functionality if the application configuration allows
- Implement network-level restrictions to limit access to the application to trusted users only until the patch can be applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
