CVE-2026-77144: Frontend Management Plugin Auth Bypass

CVE-2026-77144 Overview

CVE-2026-77144 is a broken access control vulnerability in a TYPO3 frontend event management plugin. The plugin attributes newly created events to the submitting user's organizer record only when the request contains no organizer field. The permission check validates only that the submitting user holds any organizer role, not that they own the organizer record referenced in the request. An authenticated user with frontend event management access can therefore create events attributed to another organizer, undermining data integrity and organizer accountability.

Critical Impact
Authenticated frontend users can create events attributed to arbitrary organizer records, breaking authorization boundaries between organizer identities [CWE-915].

Affected Products

TYPO3 event management extension (see TYPO3 Security Advisory 2026-026)
Installations exposing the frontend event creation plugin to authenticated users
Deployments where multiple organizer records coexist under frontend management

Discovery Timeline

2026-08-25 - CVE-2026-77144 published to the National Vulnerability Database (NVD)
2026-08-27 - Last updated in NVD database

Technical Details for CVE-2026-77144

Vulnerability Analysis

The flaw is an improper authorization defect classified under [CWE-915] (Improperly Controlled Modification of Dynamically-Determined Object Attributes). The event creation endpoint accepts an organizer identifier from the client request. If the field is omitted, the plugin defaults the organizer to the submitting user's own organizer record. If the field is supplied, the plugin trusts the provided value after only confirming that the submitter possesses some organizer role. The endpoint does not verify that the submitter is authorized to act on behalf of the referenced organizer record.

This breaks tenant isolation between distinct organizer entities managed through the same frontend. Attackers gain limited data integrity impact by fabricating events under another organizer's identity, which can mislead attendees, distort registration workflows, and damage the reputation of the impersonated organizer.

Root Cause

The root cause is a missing object-level authorization check on the organizer reference passed in event creation requests. The plugin conflates "user holds any organizer role" with "user may write on behalf of this specific organizer." The condition to attribute events to the submitter fires only when the organizer field is absent, allowing clients to override attribution simply by supplying a value.

Attack Vector

Exploitation requires network access to the TYPO3 site and low-privilege authenticated access to the frontend event management functionality. The attacker submits an event creation request that includes a chosen organizer identifier belonging to another party. The backend accepts the value and stores the event under the specified organizer without further ownership validation. No user interaction beyond the attacker's own submission is required.

For technical details on the flaw and affected versions, see the TYPO3 Security Advisory 2026-026.

Detection Methods for CVE-2026-77144

Indicators of Compromise

Events in the TYPO3 database where the creating frontend user account does not match any account historically associated with the referenced organizer record
Frontend POST requests to the event creation endpoint containing an explicit organizer identifier from accounts that previously omitted the field
Sudden appearance of events attributed to organizers who have not authenticated within the relevant timeframe

Detection Strategies

Correlate frontend session identity with the organizer field submitted in event creation requests and alert on mismatches
Review TYPO3 extension logs and web server access logs for POST requests to the event submission handler that include organizer parameters
Run periodic database queries comparing event authorship metadata against organizer ownership relationships

Monitoring Recommendations

Forward TYPO3 application and web server logs to a centralized SIEM for behavioral analysis
Baseline the volume and origin of frontend event creation requests and alert on deviations
Monitor administrative dashboards for newly created events lacking a corresponding registration or communication trail from the attributed organizer

How to Mitigate CVE-2026-77144

Immediate Actions Required

Apply the patched extension version referenced in TYPO3 Security Advisory 2026-026 as soon as it is available in your environment
Audit events created since the plugin was deployed to identify records attributed to organizers the submitter did not own
Restrict frontend event management group membership to trusted users pending remediation

Patch Information

Refer to the TYPO3 Security Advisory 2026-026 for the fixed extension versions and upgrade guidance. The patched release enforces that the submitting user owns the organizer record referenced in an event creation request.

Workarounds

Temporarily disable the frontend event creation plugin or restrict it to a single-organizer configuration until patching is complete
Add a server-side validation layer or TypoScript condition that rejects requests where the submitted organizer identifier differs from the authenticated user's organizer record
Reduce frontend event management privileges to a minimal set of vetted accounts

bash

# Example: identify recently created events for manual ownership review
# Replace table and column names to match your extension schema
mysql -u typo3 -p typo3db -e "SELECT uid, title, organizer, cruser_id, crdate \
  FROM tx_eventmgmt_domain_model_event \
  WHERE crdate > UNIX_TIMESTAMP('2026-01-01') \
  ORDER BY crdate DESC;"