Stored XSS by authenticated backend user with access to upload files
Impact
Backend users with access to upload files were permitted to upload SVG files without any sanitization applied to the uploaded files. Since SVG files support being parsed as HTML by browsers, this means that they could theoretically upload Javascript that would be executed on a path under the website's domain (i.e. /storage/app/media/evil.svg), but they would have to convince their target to visit that location directly in the target's browser as the backend does not display SVGs inline anywhere, SVGs are only displayed as image resources in the backend and are thus unable to be executed.
Patches
Issue has been patched in Build 469 (v1.0.469) & v1.1.0.
Workarounds
Apply https://github.com/octobercms/library/commit/80aab47f044a2660aa352450f55137598f362aa4 to your installation manually if unable to upgrade to Build 469 or v1.1.0.
References
Reported by Hoan Hoang
For more information
If you have any questions or comments about this advisory:
- Email us at hello@octobercms.com
Threat assessment:
<img width="1107" alt="Screen Shot 2020-10-10 at 1 47 49 PM" src="https://user-images.githubusercontent.com/7253840/95663787-378f2b80-0aff-11eb-8dfc-b97d162939da.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, < 1.0.469 | 1.0.469 |
References
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- Composer
- Package
october/backend- Disclosed
- 23.11.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-fx3v-553x-3c4q - 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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Stored XSS by authenticated backend user with access to upload files this entry
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