Skip to main content

TYPO3 Mask Extension CVE-2026-77139

| EUVDEUVD-2026-65337 MEDIUM
Path Traversal (CWE-22)
2026-08-25 TYPO3 GHSA-q7c6-98mw-7m48
6.0
CVSS 4.0 · Vendor: TYPO3
Share

Severity by source

Vendor (TYPO3) PRIMARY
6.0 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
5.9 MEDIUM

AC:H maps the CVSS 4.0 AT:P condition (Mask module access required); PR:L for authenticated backend user; no confidentiality impact; low availability from file deletion.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:L
4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (TYPO3).

CVSS VectorVendor: TYPO3

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

2
Patch available
Aug 25, 2026 - 11:01 EUVD
Analysis Generated
Aug 25, 2026 - 09:46 vuln.today

DescriptionCVE.org

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.

AnalysisAI

Path traversal in the TYPO3 Mask extension allows authenticated backend users with Mask module access to create or delete arbitrary .html files outside the configured template directory. The flaw stems from the extension's failure to validate client-supplied template element keys before using them to construct filesystem paths for saving and deleting Mask template files. …

Unlock full vulnerability intelligence

  • Risk assessment & exploitation conditions
  • Attack chain visualization
  • Remediation with exact patch versions
  • Threat intelligence from 22 sources
  • Personal watchlist & email alerts

Free forever · No credit card required

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Authenticate to TYPO3 backend
Delivery
Access Mask module with permitted role
Exploit
Submit template key containing path traversal sequences
Execution
Extension builds unsanitized file path
Persist
Create or overwrite .html file outside template directory
Impact
Potentially inject content into web-accessible template

Vulnerability AssessmentAI

Exploitation Exploitation requires two specific conditions: (1) the attacker must hold a valid, authenticated TYPO3 backend account (PR:L - unauthenticated access is not sufficient), and (2) that account must be explicitly granted access to the Mask module within the TYPO3 backend (reflected as AT:P in the CVSS 4.0 vector). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 score of 6.0 reflects a calibrated balance: VI:H (high integrity on the vulnerable system) is partially offset by AT:P (a specific module-access prerequisite) and VA:L. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker with a TYPO3 backend account and Mask module permissions submits a crafted content element key such as '../../webroot/error_page' when saving a Mask template. The extension constructs a file path by appending '.html' to the key without sanitization, causing the server to write attacker-controlled HTML content to a file outside the template directory - for example, overwriting an existing error page or creating a new web-accessible file. …
Remediation The primary remediation is to upgrade to the patched version of the TYPO3 Mask extension as specified in the vendor advisory at https://typo3.org/security/advisory/typo3-ext-sa-2026-017 - the exact fixed version number must be confirmed there, as it was not included in the available data. … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

Share

CVE-2026-77139 vulnerability details – vuln.today

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy