CVE-2026-4202: Information Disclosure Vulnerability

CVE-2026-4202 Overview

CVE-2026-4202 is an information disclosure vulnerability affecting a TYPO3 extension where the application fails to properly verify whether an authenticated user has the necessary permissions to access redirect records. This broken access control issue results in unauthorized exposure of redirect configuration data when users edit pages within the TYPO3 content management system.

Critical Impact

Authenticated users without proper authorization can access sensitive redirect records, potentially exposing internal URL mappings, site structure information, and redirect configurations that should be restricted to administrators.

Affected Products

• TYPO3 Extension (specific versions not disclosed in advisory)

Discovery Timeline

• 2026-03-17 - CVE CVE-2026-4202 published to NVD
• 2026-03-17 - Last updated in NVD database

Technical Details for CVE-2026-4202

Vulnerability Analysis

This vulnerability falls under CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The core issue stems from missing authorization checks within the TYPO3 extension's redirect management functionality. When an authenticated user navigates to edit a page, the extension fails to validate whether that user possesses the appropriate permissions to view associated redirect records.

The vulnerability requires network access and an authenticated session to exploit. While the attacker must have some level of authentication to the TYPO3 backend, they do not need elevated privileges to access the exposed redirect data. This represents a horizontal privilege escalation scenario where users can access data outside their intended authorization scope.

Root Cause

The root cause is an improper access control implementation where the extension does not enforce permission checks before displaying redirect records. The authorization logic that should verify user permissions against the redirect resource is either missing or improperly implemented, allowing any authenticated backend user to view redirect configurations they should not have access to.

Attack Vector

The attack requires an authenticated user to access the page editing functionality within TYPO3. When loading the page editor, the extension retrieves and displays redirect records without validating the user's authorization level. An attacker with basic backend access can enumerate and view redirect configurations, potentially gaining insight into:

• Internal URL structures and site architecture
• Redirect destinations that may reveal internal systems
• Configuration patterns that could aid further attacks

The exploitation is straightforward - the attacker simply needs to navigate to a page edit interface to trigger the unauthorized data exposure.

Detection Methods for CVE-2026-4202

Indicators of Compromise

• Unusual access patterns to page editing interfaces by users who typically do not require such access
• Backend audit logs showing redirect record queries from users without redirect management permissions
• Anomalous API calls or database queries accessing redirect tables from unauthorized session contexts

Detection Strategies

• Implement audit logging for all redirect record access attempts and monitor for access by non-privileged users
• Review TYPO3 backend access logs for patterns indicating users accessing page edit functions outside their normal workflow
• Deploy web application firewall rules to detect and alert on unexpected redirect data retrieval patterns

Monitoring Recommendations

• Enable detailed TYPO3 backend logging and centralize logs for security analysis
• Set up alerts for any access to redirect management functions by users not in the administrator group
• Regularly audit user permissions to ensure principle of least privilege is maintained

How to Mitigate CVE-2026-4202

Immediate Actions Required

• Review the TYPO3 Security Advisory for specific patch information and affected versions
• Audit current user permissions and remove unnecessary backend access from users who do not require page editing capabilities
• Temporarily restrict access to page editing functions until the patch can be applied
• Review access logs to determine if this vulnerability has been exploited

Patch Information

Consult the official TYPO3 Security Advisory for the specific extension version that addresses this vulnerability. Apply the vendor-provided patch as soon as possible following your organization's change management procedures.

Workarounds

• Implement custom access control middleware to validate redirect record permissions before display
• Restrict backend user access using TYPO3's built-in user group permission system to limit who can access page editing functions
• Consider disabling the affected extension functionality until a patch is available if redirect management is not business-critical
• Use network-level controls to limit backend access to trusted IP addresses only

# TYPO3 CLI command to clear caches after applying security updates
./vendor/bin/typo3 cache:flush --force