Stored XSS in October
Impact
A user with access to a markdown FormWidget that stores data persistently could create a stored XSS attack against themselves and any other users with access to the generated HTML from the field.
Patches
Issue has been patched in Build 466 (v1.0.466) & RainLab.Blog v1.4.1 by restricting the ability to store JS in markdown to only users that have been explicitly granted the backend.allow_unsafe_markdown permission.
Workarounds
Apply https://github.com/octobercms/october/commit/9ecfb4867baae14a0d3f99f5b5c1e8a979ae8746 & https://github.com/rainlab/blog-plugin/commit/6ae19a6e16ef3ba730692bc899851342c858bb94 to your installation manually if unable to upgrade to Build 466 or v1.4.1 of RainLab.Blog (if using that plugin).
References
Reported by Sivanesh Ashok
For more information
If you have any questions or comments about this advisory:
- Email us at hello@octobercms.com
Threat assessment:
<img width="1100" alt="Screen Shot 2020-03-31 at 2 01 52 PM" src="https://user-images.githubusercontent.com/7253840/78070158-8f7ef580-7358-11ea-950c-226533f6a0a3.png">Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | october/backend | >= 1.0.319, < 1.0.466 | 1.0.466 |
References
- https://github.com/octobercms/october/security/advisories/GHSA-w4pj-7p68-3vgv
- https://nvd.nist.gov/vuln/detail/CVE-2020-11083
- https://github.com/octobercms/october/commit/9ecfb4867baae14a0d3f99f5b5c1e8a979ae8746
- https://github.com/rainlab/blog-plugin/commit/6ae19a6e16ef3ba730692bc899851342c858bb94
- http://packetstormsecurity.com/files/158730/October-CMS-Build-465-XSS-File-Read-File-Deletion-CSV-Injection.html
- http://seclists.org/fulldisclosure/2020/Aug/2
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Composer
- Package
october/backend- Disclosed
- 05.08.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-w4pj-7p68-3vgv - CC BY 4.0
Vulnerability history: october/backend
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 7
- First → latest
- 06.2020 03.2021
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 2
- Low 5
Disclosures per year
- 2020: 6
- 2021: 1
- 2022: 0
- 2023: 0
- 2024: 0
- 2025: 0
- 2026: 0
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