CVE-2020-15249
MEDIUMStored XSS by authenticated backend user with access to upload files
Blast Radius
october/backendReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
October is a free, open-source, self-hosted CMS platform based on the Laravel PHP Framework. In October CMS from version 1.0.319 and before version 1.0.469, 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. Issue has been patched in Build 469 (v1.0.469) & v1.1.0.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | october/backend | ≥ 1.0.319&&< 1.0.469 | 1.0.469 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for october/backend. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update october/backend to 1.0.469 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15249 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2020-15249 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2020-15249. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2020-15249 in your dependencies?
O3 detects CVE-2020-15249 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.