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

> Authenticated backend users can read arbitrary files, including sensitive configuration, via path traversal in LESS compilation.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Aug 2026
- **Updated:** 26 Aug 2026
- **Also known as:** GHSA-58fp-mcx6-7qf9

## What is CVE-2026-63179?

CVE-2026-63179 is a medium-severity path traversal vulnerability in wintercms winter, published on 26 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official 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.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-63179?

2 open source packages ship an affected version, including winter/wn-backend-module.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `winter/wn-backend-module` | Packagist | All versions | 1.2.13 |
| `winter/wn-backend-module` | Packagist | All versions | 1.2.13 |

## How do I fix CVE-2026-63179?

Upgrade winter/wn-backend-module to 1.2.13 or later.

## Is CVE-2026-63179 being exploited?

There is no known exploitation of CVE-2026-63179 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63179 and fix it if it is affected.

What it is: CVE-2026-63179 is a medium-severity path traversal vulnerability in wintercms winter, published on 26 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-63179 in the wild and no public exploit code.

Affected packages and fixed versions:
- winter/wn-backend-module (Packagist): affected all versions; fixed in 1.2.13
- winter/wn-backend-module (Packagist): affected all versions; fixed in 1.2.13

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-63179/ (Markdown: https://insights.sbomify.com/CVE-2026-63179/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63179
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63179
- OSV: https://osv.dev/vulnerability/CVE-2026-63179

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63179/
Summaries are generated and may contain mistakes; the official description above is the record.