---
id: CVE-2026-77139
title: >-
  The extension fails to validate a client-supplied template element key before
  using it to build file paths for saving and deleting Mask template files
summary: >-
  The extension fails to validate a client-supplied template element key before
  using it to build file paths for saving and deleting Mask template files. An
  authenticated backend user with access to the Mask module can supply a key
  contain…
severity: none
cwe:
  - CWE-22
  - CWE-73
published: '2026-08-25'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T23:10:00.143'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77139'
references:
  - url: 'https://typo3.org/security/advisory/typo3-ext-sa-2026-017'
    label: f4fb688c-4412-4426-b4b8-421ecf27b14a
tags:
  - nvd
ingestedAt: '2026-09-28T23:23:00.542Z'
---

## Overview

The extension fails to validate a client-supplied template element key before using it to build file paths for saving and deleting Mask template files. An authenticated backend user with access to the Mask module can supply a key containing path traversal sequences to create or delete .html files outside the configured template directory.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.